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FRONT
Black Tiger badis Dario sp. Photo: Andrew Coffey
- Anubias revisited by Darren Stevens
FISH PROFILE - Betta pugnax by Maxine Lynch
A popular classic- Xiphophorus maculatus
FISH FAMILY PROFILE - Corys- it's a little bit complicated by Darren Stevens
FISH PROFILE - Buenos Aires tetra
Welcome to a new issue of Aquarium World.
In New Zealand, winter is behind us, daylight saving has started, and the days are getting longer. It’s a great time to start doing some maintenance on your outdoor pond or to start a new aquarium project.
You may have a small aquarium that could do with a makeover. In this issue we feature the black tiger badis, a delightful little species which is a great option for a well planted nano tank.
If you are a fan of bettas then why not try something different, like Betta pugnax , a striking mouthbrooding species from Peninsular Malaysia?
Corys are deservedly popular, and they come in a wide range of body shapes and colour patterns. However, late last year things got more complicated with corys when they underwent a major scientific revision. There are now seven separate groups (genera) of corys and many of our favourite species have had a scientific name change. In this issue I try and explain these changes.
And finally, on the aquatic plant front, Melanie introduces us to the remarkable aroids, a diverse and unusual family of plants, some of which are suitable for aquaria, and I take another look at Anubias and introduce some great new tissue cultured imports.
Darren Stevens FNZAS Editor
Gastrodermus hastatus
Photo: Paulo Robson de Souza
OPEN 7
9:30AM - 5:30PM
Andrew Coffey
Andrew can’t remember a time as a child that he wasn’t keeping tadpoles, frogs and fish from local ponds There have been times in his life that he has been in remission but he freely accepts that he has been afflicted by ‘MTS’ for the best part of 30 years. In the past he has kept and bred a variety of Plecos, African cichlids, and rainbow fish. Currently he is keeping and breeding Tanganyikan cichlids, Victorian haps and is trying his luck with apistogrammas and various oddballs.
Maxine has been a fish keeper for most of her life, with a passion to continue killifish strains in New Zealand, to ensure that as many varieties of this beautiful species are available to future fish keepers. With a passion for nano fish, most of her fish-garage is made up of tanks of less than 200L, with the exception of a 1000L tank that was put in for rescues. Maxine is a public servant and has held various roles in her time in the FNZAS.
Darren is a marine biologist who has worked for NIWA for about 20 years. He regularly participates in research surveys and has been around much of New Zealand as well as Oman, UAE, and the Ross Sea, Antarctica. In his spare time he enjoys fishing, and is a particularly passionate pleco keeper. Darren is an active participant in his local clubs and
Melanie returned to fish keeping after a 25 year break. She originally studied botany and is as keen on plants as well as fish. Her tanks are mainly planted, aquascaped community tanks. She also has a lifelong interest in invasive species, especially invasive plants.
Advertising for the Aquarium World magazine and the Aquarium World website is managed by the FNZAS and can be arranged by emailing: president@fnzas.org.nz Accounts: Patricia Lynch treasurer@fnzas.org.nz
Sept 1995 – Feb 2013: Caryl Simpson caryl@simtronics.co.nz Post Feb 2013: diane@scratchmedia.co.nz
The black tiger badis (Dario sp.) is a delightful little freshwater fish from Northern Myanmar that is popular in the nano fish hobby. They are a member the badis family (Badidae) which are commonly known as chameleon fish due to their ability to change colours.
Nano’s Colourful Tiger
by Andrew Coffey
Black tiger badis pair courting
Photo: Andrew Coffey
There are about 30 badid species that inhabitant freshwater environments across Asia from Pakistan to Thailand. The largest species gets to about 8 cm while the smallest barely gets to 2 cm. The black tiger badis grows to about 3 cm for males while females are smaller.
I have kept three types of badis: the blue badis (Badis badis), the scarlet or rainbow badis (Dario dario) and the black tiger badis (Dario sp.) and they all seem to require similar care and feeding. (note: I have kept scarlet badis, but I was not able to breed them as females are notoriously hard to come by).
Tank set up. I have found that black tiger badis do well in a planted and mature tank with a sandy substrate and plenty of leaf
above: Male scarlet badis (Dario dario)
Photo: Andrew Coffey
top right: Male blue badis (Badis badis)
Photo: Andrew Coffey
right: Black tiger badis breeding tank
Photo: Andrew Coffey
litter/botanicals for the fish to hide and forage in.
Water conditions should be soft with a fairly neutral pH. The pH of my breeding set up is in the high 6’s although I have read reports of people keeping them in much higher pH ranges. I keep the temperature between 23–26°C and they appear happy to breed in that range. I tend to keep my lighting subdued as I want a naturalistic feel to the tank and I also think it adds less stress as they like the dimmer parts of the tank.
Feeding. Live food is a must for these micro-predators and I feed them daphnia and a variety of worms. I tend to feed micro and vinegar worms primarily for the fry, and white and black worms for the adults. White worms are good for fattening the adults up after the female has spawned. The leaf litter and botanicals are also a good environment for micro-organisms which become a source of food, particularly for very young fry.
Black tiger badis adult male
Photos: Andrew Coffey
Tankmates. These fish are shy and tend to be secretive, and while there can be some conspecific aggression amongst males, especially as they become sexually mature, they are a peaceful non-aggressive fish that should be kept with other ‘nano’ species of fish. I have one pair living alone in a 90-litre
Black tiger badis fry
Photos: Andrew Coffey
tank with a 60 cm footprint and I think that is about the right footprint for a male’s territory. I have seen it suggested that more males could work in a tank of this size but any males are likely to be subdominant, less likely to colour up, and even run the risk of being killed by the alpha male. Breeding. Males are territorial. I supplied a cave and some tangled wood for my male to base himself around. Once a territory is established, a male will actively chase
back tiger badis
Photos: Andrew Coffey
females and other males away until a gravid female is allowed to approach, and then he will display for her. She tends to be submissive and then the male will allow her into his territory where they will spawn and scatter eggs. I find a good amount of moss is a great medium for spawning as
Photos: Andrew Coffey
Gravid female
Young black tiger badis (8mm)
it allows the eggs to be hidden from being consumed by the parents.
The fry seem to start showing themselves at about 3 mm and the parents pay little or no attention to them. At about 8 to 10 mm, they start to be sexable. Males tend to be longer and narrower, like a torpedo, and eventually develop the dark head and vertical red barring, while females tend to
be shorter and have a squatter body shape. A gravid female will become very plump.
I have been transferring the young black tigers to a 1 metre long 200 litre ‘grow out’ tank. I plan on selling a few and building up a community to keep myself.
community ‘grow out’ tank
Photo: Andrew Coffey
It already looks like I have two males taking either side of the tank and the rest of the males and females are happily keeping out of their way. The tank is heavily planted, mainly with Anubias nana, Java fern, Java moss, and a few crypts, which cover the floor of the tank, and some duck weed on the surface. I rarely see them swimming far from the bottom of tank or in open water.
As of writing this article, I have just added some dwarf spotted danios to the community tank as they are from the same region to create a slightly SE Asian feel to the tank.
Andrew Coffey
Anubias revisited
Since the last issue there have been some great tissue culture imports, including the stunning and locally rare onion plant Crinum calamistratum, some great crypts (including Cryptocoryne albida (AKA C. costata) and Cryptocoryne pontederifolia), and the striking Bacopa caroliniana ‘colorata’. Recent months have also seen the introduction of new tissue culture ranges from Aqua Art, Aquascaping Essentials, and Highway Fisheries. The future certainly looks bright for aquatic plant enthusiasts.
Several new Anubias cultivars have also been imported and, given my fascination for these striking plants, I thought it timely to
revisit the Anubias we have in New Zealand. Here are a few new imports and updates that didn’t make the last article. And just a word of caution, many Anubias varieties are remarkably similar, some are often sold under other incorrect names, and this leads to confusion over the identity of some varieties.
Anubias barteri var. angustifolia
Anubias b. angustifolia has long narrow to narrow oval (5–9 times longer than wide, up to 3.5 cm wide, widest at about the middle) leaves that can grow to about 18 cm. The petioles (leaf stalk) are 0.5-1 times the leaf length. It is apparently the Anubias barteri variety with the narrowest leaves. The
imported plants are stunning but have broad leaves and may be a different cultivar. True A. b. angustifolia is similar to A. b. glabra (AKA A. minima) but generally has narrower leaves with a straight (not ruffled) leaf margin and often reddish-brown leaf stalks. Overseas, A. b. angustifolia is apparently often sold as A. afzelii.
Anubias barteri var. glabra (AKA Anubias minima)
A. b. glabra has been in New Zealand for many years but regular, variegated, ‘dragons claw’, and the delightful small ‘mini chili’ varieties have recently been imported. It will be interesting to see if the new variegated imports retain their variegation, as the New Zealand variegated plants now rarely produce a variegated leaf. Dragons claw apparently has narrow, slightly crinkled (ruffled) leaves, resembling a dragons claw! The tissue cultured ‘dragons claw’ imports look similar to existing New Zealand plants, but I have yet to see a large plant.
Anubias b. glabra ‘mini chili’ has small dark green pointed leaves and a compact bushy growth habit. It is another very small cultivar, and is named for its small leaves which resemble mini chili peppers. It is smaller than A. b. nana ‘petite’ and resembles A. b. nana ‘pangolino’ in size but apparently Anubias b. glabra ‘mini chili’ has broader, more convex leaves, with a more obvious central vein.
Anubias barteri var. nana ‘bonsai’
Another great small cultivar of Anubias b. nana. It looks very similar to A. b. nana ‘petite’ but is even smaller.
Anubias b. glabra ‘mini chili’
Photo: Darren Stevens
Anubias b. glabra ‘mini chili’ Photo: Darren Stevens
Anubias b. nana ‘bonsai’
Photo: Darren Stevens
Anubias b. nana ‘bonsai’
Photo: Darren Stevens
Anubias b. nana ‘pangolino’
A beautiful new very small Anubias b. nana cultivar with dark green leaves. It was discovered in the Dennerle Plants nursey in Germany in their Anubias b. nana ‘bonsai’ stocks and is possibly the smallest Anubias cultivar. It is named after the pangolin (scaly anteater) as it has a very compact growth habit with leaves that often overlap resembling a pangolin’s scales. Anubias hastifolia
A very large Anubias with long variable oval to arrowhead-shaped leaves (to 33 cm) and long leaf stems (to 67 cm). It has been in New
Zealand for many years but is not popular due to its large size. It will grow submerged (and remain much smaller and with shorter stems) but it only thrives when grown emersed. It has recently been imported as tissue-cultured imports. It is similar to, often confused with, and sometimes sold as Anubias gigantea. It is not known if true A. gigantea is present in NZ
These new additions are great news for aquatic plants fans but identifying them has got a lot more complicated. While some Anubias cultivars are distinctive (e.g., the round leaved A. b. barteri ‘golden coin’ or A. b. nana ‘minicoin’), many are remarkably similar and difficult to identify. For example, A. b. nana and A. b. nana ‘petite’ have often been confused and now you can add A. b. nana ‘bonsai’, A. b. nana ‘pangolino’, and Anubias b. glabra ‘mini chili’ to the mix. So, it pays to keep track of what plants you have and what you are buying. Tissue cultured plants are a great option as they offer quality, diseasefree plants of known origin. And while they may seem expensive you generally get several plants in a pottle.
Thanks to ‘The Aquascape Shop’ for allowing us to use their images.
Darren Stevens
Anubias b. nana ‘pangolino’
Photo: The Aquascape Shop
Anubias hastifolia
Photo: The Aquascape Shop
Anubias hastifolia
Betta pugnax
The Penang or forest betta (Betta pugnax) is native to Southeast Asia, where it is found in fast flowing forest streams. They are a mouthbrooding betta species and can grow to a length of 10–14 cm.
Penang betta can be housed as pairs, either in their own tank or in a peaceful wellplanted community tank. My Betta pugnax are kept in their own tank with a few bronze corys. Their tank has driftwood and needle leaf java fern filling most of it and a top cover of duckweed to help them feel safe from predators. Their tank gets a lot of algae as it is near windows.
Male Penang betta have a broader head than females, much longer pelvic fins, and spikes on their anal and caudal fins (caudal fins are often spear shaped). They also develop “green/blue cheek flashes”. Females tend to develop brown horizontal breeding stripes.
During breeding, the male and female will embrace at the bottom of the tank. After the eggs are fertilised, both fish will collect the eggs and they are passed to the male. He will hold them in his mouth for the full incubation period, which can be up to three weeks. My Betta pugnax spawn regularly. I generally move the holding male to his own tank until he releases the fry. Fry will eat baby brine shrimp as soon as they are released and are avid feeders.
Maxine Lynch
Photo: Fish-Garage-NZ
Betta pugnax pair - Female on right hand side
Photo: Fish-Garage-NZ
Male holding eggs
Photo: Fish-Garage-NZ
Male photographed in the Upper Seletar Reservoir Park, Singapore
Photo: zicky
A Popular Classic
Platies are a great beginners’ fish. They come in a large range of colours young. There are two species: the southern platy Xiphophorus maculatus strains are hybrids of both species. Platies grow to about 7 cm and
colours and patterns, are easy to keep, and they give birth to live maculatus and the variable platy X. variatus, although most aquarium and prefer a well planted tank.
Blue calico platy Photo: Robert Beke
Corys
– it’s a little bit complicated
Corys (subfamily Corydoradinae) have been in the hobby for many years. Peppered corys were first bred by Parisian Piere Carbonier in 1878, but prior to the 1960’s there were very few species in the hobby. There are now over 200 scientifically described cory species and even more varieties awaiting a scientific name.
The undescribed varieties are often assigned a C- or CW-number. C-numbers were created by HansGeorg Evers for the German fishkeeping magazine DATZ in 1993 and the system was used up until 2009. It was superseded by CW (Corydoras World) numbers, created by Ian Fuller and Hans-Georg Evers. These semi-scientific classification systems are similar to the LDA- and L-numbers given to plecos
Darren Stevens
A generalized ‘Corydoras’ showing key measurements and counts
Figure: Nijssen & Isbrücker, 1967
and were developed to keep track of the many new cory varieties that enter the hobby.
In New Zealand, we have 82 cory species on the approved ornamental fish import list: the sixray cory, Gastrodermus (formerly Aspidoras) pauciradiatus, the green (emerald) cory Brochis splendens, the giant brochis Brochis britskii, the bearded cory Scleromystax barbatus, and 78 species of ‘Corydoras’.
I say ‘Corydoras’ because late last year things became more complicated with corys. You might have noticed that the scientific names of many
corys has changed. For example, the popular bronze cory Corydoras aeneus is now Osteogaster aenea, and the peppered cory, Corydoras paleatus is now Hoplisoma paleatum. This can be confusing, so I thought it might be worth revisiting these changes. I am far from a cory expert but, fortunately, the cory gurus have written several great scientific publications and popular articles, which were a great help in writing this.
You might be thinking, why change the scientific names? Well, while it is convenient to lump most corys in the genus Corydoras (there are exceptions, e.g. Aspidoras, Scleromystax, and, until 2003, Brochis) this doesn’t account for the large range of head shapes (e.g. snout length varies from short and rounded to long and saddle-shaped) body shapes, maximum size, behaviour and reproduction, that had been noted by scientists and aquarists for many years. And genetically they form distinct groups (lineages), so splitting them into separate genera (plural of genus), i.e. groups of similar related species with shared characters, makes sense and was long overdue.
The taxonomy (scientific classification) of corys has had a long and complex history with several genera being proposed and most ultimately being considered non-valid (synonymised). In 1980, Nijssen and Isbrücker tackled the large variety of corys by proposing five groups based on colour patterns and shared characters: the ‘punctatus’ group, the ‘barbatus’ group, the ‘aeneus’ group, the ‘elegans’ group, and the ‘acutus’
group, useful divisions that are still sometimes used today.
More recently, based on decades of scientific study and advances in genetic barcoding, two landmark studies were published. In 2011, Alexandrou et al. found large genetic differences (based on mitochondrial DNA) between cory species and proposed nine distinct groups (lineages 1–9). These divisions largely backed up what the expert cory keepers had been noticing for years and were adopted by hobbyists for placing corys into logical related groups.
Late in 2024, Dias et al. conducted a major revision of the subfamily Corydoradinae (corys and related species), a monumental task that used genetic and morphological (physical characters such as size, shape, colour, and form, e.g. eye diameter, head length, snout shape, number of fin rays, colour pattern) data. They concluded that all Corydoradinae had descended from a common ancestor and that genetically and morphologically they were comprised of seven groups, each representing a different genus.
The seven recognised cory genera are: Aspidoras, Brochis, Corydoras, Gastrodermus, Hoplisoma, Osteogaster, and Scleromystax; and while some genera may eventually be split further, this is a hugely significant shake up of corys. These genera were either currently in use ( Aspidoras, Corydoras, and Scleromystax) or resurrected older names that were considered non-valid (synonymised, Brochis, Gastrodermus, Hoplisoma, and Osteogaster ). They
largely follow the groups (lineages) used in Alexandrou et al. (2011): Corydoras (Lineage 1, L1), Aspidoras (L2), Scleromystax (L3), Gastrodermus (L4 and L5), Osteogaster (L7), Brochis (L8, comprises subclades 8a–8d), and Hoplisoma (L6 and L9).
Hans-Georg Evers summarised these seven genera in his excellent 2024 Amazonas magazine article, and I have relied heavily on his summaries in the following breakdown of each genus. There are also many more technical diagnostic characters for each genus, such as the relative size and shape of various skull bones or the direction of serrations on the dorsal and pectoral fin spines, in Dias et al. (2024) that are not included here.
Corydoras (lineage 1)
There are now only 32 scientifically described true Corydoras species, and several coded varieties (i.e. with a C- or CW-number). They are also known as ‘saddle-snouts’ as the top of the snout has a long, slightly concave (saddle-
shaped) profile. True Corydoras also have a long body (compared to other corys), an eyebrow-like marking above the eyes, and most species have a small, roughly triangular, fleshy flap at the corner of the mouth which may look like a small barbel. There are 10 true Corydoras species on the approved import list, but they are rarely imported into New Zealand. Although, with their long snouts and often impressive patterning, they would likely be popular.
Aspidoras (lineage 2)
Are small (to about 5 cm) long catfish with a small head and small eyes
Above - Long nosed arched cory Corydoras narcissus and top right - Pastaza cory C. pastazensis
Photos: Blair Chen
Sixray cory Gastrodermus pauciradiatus
Photo: Michael Noren
Top - darkspotted bulldog cory Aspidoras fuscoguttatus
(compared to other corys). There are 18 scientifically described species and a few coded varieties. Many have similar variable patterning, making them difficult to identify. The six ray cory (formerly Aspidoras pauciradiatus) has been occasionally imported into New Zealand. However, it is now considered to be a cory and has been placed in Gastrodermus, i.e., Gastrodermus pauciradiatus (Tencatt et al. 2022).
Scleromystax (lineage 3)
Contains seven scientifically described species and a similar number of coded varieties. They are all from southeastern Brazil and tend to be elongate with black
and white patterning and adult males have small beard-like bristles (odontodes) on the cheeks. The striking bearded cory, Scleromystax barbatus, which can grow to over 10 cm, is sometimes imported into New Zealand.
Bearded cory Scleromystax barbatus
Photo: Birger A
Gastrodermus (lineages 4 and 5)
Comprises 14 described species, and more coded varieties, all of which have a very short head, and a high-backed oval body. The lineage 4 species (G. pygmaeus, G. hastatus, G. guapore, G. mamore, G. paucerna) are genetically
Pygmy cory Gastrodermus pygmaeus (lineage 4)
Photo: Robert Beke
Top - Salt and pepper cory G. hastatus (lineage 4)
Middle - Nijssen's cory G. nijsseni (lineage 5)
Bottom - Rio Napo cory G. napoensis (lineage 5)
Photos: AquariaNR, Blair Chen & Sophie Graul
distinct but currently lack sufficient diagnostic characters to place them in their own genus, although this may change in the future (if this happens the genus Microcorydoras would be resurrected). The pygmy cory G. pygmaeus, salt and pepper or Rio Salinas cory G. hastatus, and elegant cory G. elegans are regularly imported into New Zealand.
Osteogaster (lineage 7)
A small group of seven greenish cory species and more coded varieties. They have a relatively short head, and often a darker back and a black mask. The bronze corydoras, Osteogaster aenea (it was C. aeneus) is common in the hobby
and found over a large area in the wild. There are several geographic varieties of O. aenea, which may prove to be separate species in the future. Some of these varieties have been imported into New Zealand including the striking green lazer cory (CW009), gold lazer cory (CW010), and the Venezuelan orange cory (O. ‘venezuelanus’ – currently not considered to be a valid scientific name). Brochis (lineage 8, subclades 8a to 8d, and the ‘long-snout’ group)
You may be familiar with the green (emerald) cory Brochis splendens, a common stocky cory that can grow to 10 cm. It has two similar scientifically described relatives, the giant Brochis
B. britskii and the hognose Brochis, B. multiradiata (was B. multiradiatus), that we don’t tend to see in New Zealand. These three distinctive greenish corys (and a handful of coded varieties) are all stocky and have more dorsal fin rays (11–18, depending on the species) than other corys (which have 6 to 8 dorsal rays). They used to be placed in Brochis, but the genus was retired from active service (synonymised) by Britto in 2003 and they were placed in Corydoras. Dias et al. (2024) has resurrected Brochis and expanded it to include another 40 scientifically described corys, including several familiar favourites, such as Agassiz’s cory B. agassizii, spotted cory
B. ambiacus, skunk cory B. arcuatus, and Schultz's cory B. haraldschultzi. However, based on genetics, Alexandrou et al. (2011) divided Brochis into four subclades (8a–8d) and it is likely this genus will be split into more genera in the future.
Top - Green cory Brochis splendens, Bottom - Schultz's Cory B. haraldschultzii
Photos: Blair Chen
Bannertail cory B. robineae
Photos: Blair Chen
Hoplisoma (lineages 6 and 9)
Most corys are now species of Hoplisoma with 84 described species and even more coded varieties. They are small species with a rounded head (round-nosed corys), a high-backed body and often attractive patterning, and include many familiar favourites. For example, Adolfo’s cory H. adolfoi, tail spot cory H. caudimaculatum, salt and pepper cory H. habrosum, slant bar cory H. loxozonum, peppered coy H. paleatum, panda cory H. panda, and the gold leopard cory H. sterbai.
Top - Tail spot cory H. caudimaculatum
Middle - Sand’s cory H. davidsandsi
Bottom - Panda cory H. panda
Photos: Robert Beke, Blair Chen, Chronotopian
Top - Sterbai cory Hoplisoma sterbai
Middle - peppered cory H. paleatum,
Bottom - salt and pepper cory H. habrosum
Photos: Matthew Mannell, h080, Blair Chen
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So, that’s a brief look at the seven recognised cory genera. You might also have noticed that there have been several changes to the species names in Brochis, Hoplisoma, and Osteogaster. For example, the peppered cory was C. paleatus and is now H. paleatum and the bronze corydoras was C. aeneus and is now O. aenea. This is because these genera are derived from Greek words. In the Greek language nouns have three genders: feminine, masculine, and neuter (i.e., neutral) and this affects the form of the word. The genus Corydoras, derived from the Greek words ‘kory’ (helmet) and ‘doras’ (skin) is masculine while Brochis and Ostegaster are feminine and Hoplisoma is grammatically neuter so some of the species names needed to be changed slightly to reflect this. Hopefully this article and the name changes makes some sense but what does this mean for aquarists? Well, the scientific names of many corys have changed, however their common names are well established and unlikely to change so there will still be plenty of corys in the hobby. A bronze cory will still be a bronze cory even though its scientific name has changed and from a scientific (taxonomic) point of view corys are now placed in logical groups (genera) that reflect their similarities and differences. If you want more information there are several great websites that are well worth visiting (e.g., PlanetCatfish, https://www. planetcatfish.com, ScotCat, https://www. scotcat.com, Corydorasworld, https:// www.corydorasworld.com).
Darren Stevens
References
Alexandrou, M.A.; Oliveira, C.; Maillard, M.; McGill, R.A.R.; Newton, J.; Creer, S.; Taylor, M.I. (2011). Competition and phylogeny determine community structure in Müllerian co-mimics. Nature 469, 84–88. https://doi.org/10.1038/nature09660
Britto, M. R. (2003). Phylogeny of the subfamily Corydoradinae Hoedeman, 1952 (Siluriformes: Callichthyidae), with a definition of its genera. Proceedings of the Academy of Natural Sciences of Philadelphia 153(1), 119–154.
Dias, A.C.; Tencatt, L.F.C.; Roxo, F.F.; Silva, G.S.C.; Santos, S.A.; Britto, M.R.; Taylor, M.I.; Oliveira, C. (2024). Phylogenomic analyses in the complex Neotropical subfamily Corydoradinae (Siluriformes: Callichthyidae) with a new classification based on morphological and molecular data. Zoological Journal of the Linnean Society 203(3). zlae053, https://doi.org/10.1093/zoolinnean/zlae053
Correction to: Phylogenomic analyses in the complex Neotropical subfamily Corydoradinae (Siluriformes: Callichthyidae) with a new classification based on morphological and molecular data, Zoological Journal of the Linnean Society, Volume 203, Issue 4, April 2025, zlaf035, https://doi.org/10.1093/ zoolinnean/zlaf035
Dignall, J. (2022). Unravelling the arched corys. Shanes World - Catfishology. https://www. planetcatfish.com/shanesworld/shanesworld. php?article_id=573
Evers, H.-G. (2024). Taxonomic revision of the armoured catfishes: Everything new–with old names! Amazonas Sept/Oct 2024, 6–15.
McLure, R. What the heck is a CW number? SCOTCAT. COM. https://www.scotcat.com/articles/ article135.htm First published for the Milwaukee Aquarium Society (July 2020).
Tanner, S.M. (2024). Overhauled: A massive revision of the genus Corydoras. AMAZONAS Magazine, Freshwater, News & Notes. Jul 10, 2024. https://www. amazonasmagazine.com/2024/07/10/overhauled-amassive-revision-of-the-genus-corydoras/ Tencatt, L.F.C.; Britto, M.R.; Isbrücker, I.J.H.; Pavanelli, C.S. (2022). Taxonomy of the armored catfish genus Aspidoras (Siluriformes: Callichthyidae) revisited, with the description of a new species. Neotropical Ichthyology 20: e220040. https://doi. org/10.1590/1982-0224-2022-0040
Salt and pepper cory Hoplisoma habrosum (Blair Chen – see above)
Tail spot cory Hoplisoma caudimaculatum, Robert Beke
Sand’s cory Hoplisoma davidsandsi (Blair Chen – see above)
Panda cory Hoplisoma panda, Chronotopian (CC BY-SA 3.0) https://en.wikipedia.org/wiki/Hoplisoma_panda#/media/ File:Panda_Corydoras.jpg
Buenos Aires tetra
This delightful tetra has been in the hobby for over 60 years. Despite its name it is not found in Buenos Aires (a similar species is) but is widespread in waterways in Argentina, Paraguay, Uruguay and southeastern Brazil. They are hardy but appreciate clean water and under good conditions they can grow to 7.5 cm and live for 6 years. Buenos Aires tetras can be prone to fin nipping so are best kept with short-finned tank mates, and in schools of at least 6 fish. Photo Robert Beke
Aroids aquarium in the
by Melanie Newfield
Many people in New Zealand are familiar with the oddly shaped white and yellow blooms of the arum lily (Zantedeschia aethiopica). Gardeners often describe it as a plant which likes “wet feet”, preferring to grow in damp areas. It shares this character with a number of related species, and the family it belongs to, the Araceae, which are commonly referred to as aroids. A number of aroids are of interest to those who enjoy aquatic plants. This article gives an overview of the broad groups which are relevant to aquaria.
Aroids are a weird bunch indeed. To start with, they have particularly strange flowers and, although these aren’t often seen in
lily bloom
the plants we grow in aquaria, it’s worth knowing a little about them. The individual flowers are usually very small and are clustered together on a structure known as a spadix. In the familiar arum lily, the spadix is the yellow part of the bloom. Usually, the spadix is surrounded in some way by a modified leaf known as the spathe. In the arum lily, the spathe is the white part which surrounds the yellow. The whole structure is referred to as an inflorescence, which is a real mouthful. The science communicator in me can’t bring myself to call them an inflorescence in an article for non-botanists,
Arum
Photo: Alvesgaspar
but the botanist in me can’t bear to call them flowers, which is why I’ve been vague and just called them blooms.
A number of aroids are pollinated by flies and the plants go to considerable effort to make themselves appealing to their pollinators. They do this by wafting foul odours, sometimes even heating up their blooms to make the odour travel further. Many also have colours reminiscent of rotten flesh. The plants grown in aquaria don’t do this, fortunately.
The first group of aroids of interest to aquarists are not aquatic at all, but vines. The best known is the golden pothos (Epipremnum aureum), which can be easily
- golden pothos
Right - heart-leaved philodendron
Photo: Kenpei
grown with its roots in a tank. There are other aroids which can be grown this way too. I’ve got the heart-leaved philodendron (Philodendron hederaceum) growing out of my tanks. It’s a great way to remove nitrates from your water, although you may need to provide micronutrients as you would for submerged aquatic plants in your tanks. My heart-leaved philodendron does occasionally flower but golden pothos never does, unless treated with hormones, but both are easily propagated by cuttings.
Left
Photo: Mokkie
The second group of aroids are generally semi-aquatic rather than truly aquatic, although they grow well and even flower entirely under water. This is the genus Anubias, native to tropical Africa. They naturally grow in wet, shady places such as stream banks, not necessarily submerged, although they can be. They grow from a creeping stem (a rhizome), which in aquaria must be kept above the substrate (or it may rot), so this is usually attached to a piece of driftwood or rock. Propagation is from pieces of rhizome.
The only species I’ve grown is Anubias afzelii, and it seems fairly bombproof. It was in a tank where the light stopped working and I lost the fish due to a particularly nasty parasite. I switched off the heater and just left the tank sitting there for months, before moving the plant to another tank which had minimal lighting but some natural light. When that tank sprung a severe leak, I set up another tank and moved my A. afzelii across while I was cycling it. It’s now in a tank full
of Colombian zebra plecos (Hypancistrus debilittera, L129) with a small Aquaone PlantGlo light directly above it, and it’s never looked so good.
There are eight species of Anubias, four of which seem to be in New Zealand based on what I’ve read: A. afzelii, A. barteri, A. gigantea and A. hastifolia. There are a few other names, such as A. nana, but they are not separate species (e.g. A. nana is a variety of A. barteri, i.e. A. barteri var. nana - see Aquarium World 69/1 for a closer look at the varieties we have in New Zealand). In any
case, botanists suggest that the species can’t be reliably distinguished without flowers, so we largely have to call them the names they are sold under.
The third group of aroids is the genus Cryptocoryne, commonly known as crypts. There are many species, with dozens described and new species described regularly. Crypts are primarily native to Asia, ranging from Sri Lanka to southern China and down to New Guinea. They are a tricky group, with widely varying numbers of chromosomes (the structures in which DNA is packaged), suggesting a complex evolutionary history. The plants grown in aquaria are propagated by stolons, which are another kind of creeping stem.
Anubias bloom
Photo: Jes
Anubias ‘afzelii’ emersed
Photos: Darren Stevens
I’ve grown a few crypts which looked different from one another but they mostly came unnamed and I’ve never got to grips
with the different species which are here. The crypts I’ve grown have thrived in tanks with lots of plant and not too many fish, supporting the suggestion that they do best with low nitrate levels. One happily flowered underwater. Overseas, at least one has established itself in the wild in warmer parts of the USA.
There are also a couple of aquatic aroid genera which are not here to my knowledge but which I should mention for completeness. One, Lagenandra, is closely related to the crypts and comes from South Asia. The other, Bucephalandra, is from Borneo.
However, there’s one more aroid group I should mention. They are so different from the other aroids I've mentioned that even botanists have debated whether they belong or not. These are the floating aroids, the duckweeds and water lettuce. Yes, these frequently troublesome floating plants are aroids!
Water lettuce (Pistia stratiotes) is often described as a tropical species, but it’s capable of growing well in temperate areas. Because it grows rapidly and can cover water
Cryptocoryne wendtii green
Photo: Tommy Kronkvist
Cryptocoryne beckettii emersed
Photo: Jan D. Bastmeijer
Pistia stratiotes
Photo: Kurt Stüber
bodies, it is considered an invasive species. This includes in some areas with a similar climate to parts of New Zealand, such the Cape region of South Africa. It has been reported from New Zealand but is subject to a national eradication programme and is a notifiable organism, which means that all sightings must be reported to MPI on pest and disease hotline 0800 80 99 66.
There are four species of duckweed that I’m aware of in New Zealand, all but one of which are regarded as native, although they are not endemic, which means they are native to other countries too. The non-native species Landoltia punctata is sometimes known as the purple-backed duckweed
Left- Lemna aequinoctialis
Photo: KevinThiele
Landoltia punctata
Photo: Francis Stitele
Pistia stratiotes Photo: pkyeung
but in my experience, it isn’t always purplebacked. However, it can be identified easily because it has two or more roots per leaf. The two native Lemna species (L. aequinoctialis and L. disperma) have a single root per leaf.
Centre - duckweed Lemna disperma and Wolffia australiana, top and right hand specimens are tipped over showing the depth of the plant body
Photo: John Walter
Right - Wolffia australiana
Photo: Alex Fergus
Finally, there’s Wolffia australiana, one of the smallest plants in the world. I’ve never seen this one in an aquarium, but it’s worth a mention simply because it’s so interesting. The entire plant consists of a floating leaf known as a platelet, less than a millimetre long. The platelet usually just divides itself to create a new plant, but it can produce flowers which are embedded in the platelet, which go on to produce seed.
Melanie Newfield
Left - Landoltia punctata showing multiple roots per leaf Right- Lemna aequinoctialis with a single root per leaf
Photos: Jim Keesling and Peter de Lange
INTERESTING IMPORTS
The importers continue to offer a great range of fish to suit most tanks. If there is a particular fish that you are after, then it is worth asking your local fish store. It may well be on one of the importers’ lists. If the dario article has sparked your interest and you have a small, planted tank, then rainbow badis are available. Or why not try another great nano option like celestial pearl danios, emerald dwarf rasboras, clown killifish, Pacific blue eyes, threadfin rainbows, or chili rasbora? And if you have a small,
unheated, tank then white cloud mountain minnows (in standard and golden) are a great option.
For large, planted tanks, it’s hard to go past a rainbowfish tank, a stunning colourful option. Banded, black-banded (wild caught), blue (Lake Kutubu), Boseman’s, Celebes, dwarf neon, Madagascar, McCulloch’s, and red rainbows (G. incisus) are all available.
If a rock pile and African cichlids are more your style, then a Lake Malawi mbuna tank is a striking option but not without
Whitecloud mountain minnow
Photo: Robert Beke
Threadfin rainbow
Photo: Robert Beke
Glossolepis incisus Red rainbow
Photo: Jennifer Hamlin
its challenges. They are aggressive, many species will hybridise, and tank mates should be chosen with care. Several species are available including albino cobalt zebras, auratus, aurora, blue zebras, demasoni, electric yellows, johani, and snow whites. And pygmy leopard catfish (Synodontis petricola) are a striking bottom dwelling option.
And finally, if you are still a fan of corys after all the scientific name changes, then there’s plenty of choice, including popular
favourites: bronze (including albinos), green (emerald), peppered, ‘julii’, panda, pygmy, tail spot, and gold leopards (including albinos). If you are after something a little different then why not try an Adolfo’s, black, black sail, broad stripe (H. duplicareum), elegant (including wild caught), false bandit (H. melini ), gold lazer, Venezuelan orange, smudge spot, slant bar (including wild caught), or a two saddle cory (H. weitzmani )?
The editorial team
Pygmy leopard catfish - Synodontis petricola
Photo: Ad Konings
Pygmy cory - Corydoras pygmaeus
Photo: Robert Beke
Metriaclima aurora African cichlid
Photo: Miguel Jo-Avila
IMAGE SOURCES
Pg Source
5 Gastrodermus hastatus Photo: Paulo Robson de Souza (CC-BY-NC) https://inaturalist.nz/observations/178771821
26 Sketch of a Corydoras showing some methods applied for taking data, Nijssen & Isbrücker, 1967 https://www.researchgate.net/ publication/311764710_Notes_on_the_Guiana_species_of_Corydoras_Lacepede_1803_with_descriptions_of_seven_new_ species_and_designation_of_a_neotype_for_Corydoras_punctatus_Bloch_1794_-_Pisces_Cypriniformes_Callichthyidae
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Current affiliated aquarium clubs in New Zealand:
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FNZAS DISCOUNT
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GISBORNE
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HAMILTON
Hollywood Fish Farm - 10% discount on selected non-sale items
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email: hamilton@hollywoodfishfarm.co.nz
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