FEATURE
They often evoke a love-hate relationship, but you just can’t get away from them
by Rohan Mak, ZM Systems
T
he green water encouraged by the traditional carp farmers in the Far East and then Europe would be rich with live infusoria including cilates and freshwater rotifers for first feeding. The marine fish industry has had to look at marine rotifers and recreating the plankton soup as many larval species are too small to take newly hatched Artemia. The leading research labs using fish in medical and ecotoxicology projects that have relied upon lab-grown Paramecia cultures are revisiting rotifer culture to maximise fry survival rates. Whilst attempts have been made to replace livefoods with artificial diets, the protocol of co-feeding live and processed diets cannot be ignored. Through careful enrichment, rotifers can be used as a smart nutritional package to aid the development of gut bacteria, boost health and support early larval development.
Do your research and plan ahead
The Plankton Culture Manual by Frank Hoff of Florida Aqua Farms is an invaluable introduction to live food culture including microalgae, rotifers, and Artemia culture. The practical examples shown in this book are based on the experience gained from the creation and development of Instant Ocean Hatcheries and operating a commercially viable marine fish hatchery. The biggest mis-
take we have seen customers make is not planning ahead and not having well-managed cultures in place.
Where to get rotifers from
Live resting rotifer cysts are available to establish cultures and can be shipped internationally by courier or airmail service. Two rotifer species are normally available: Brachionus plicatilis (L-strain) for brackish-marine work
ZM live rotifers and live microalgae
The smaller marine S-strain Brachionus rotundiformis is sometimes available for specialist projects where a smaller prey item is required.
How to view rotifers
A basic binocular dissecting microscope with at least 20x magnification is an essential tool in managing rotifer cultures and even monitoring the density of any live microalgae
FAF resting rotifer cysts being hydrated for hatching
and Brachionus calyciflorus, used for freshwater cultures. The resting cysts are stored in vials and may be frozen for long-term storage and may be stored until you are ready to inoculate a starter culture. The dehydrated cysts will first need to hydrate in a Petri dish before completing the incubation process and hatching 48 plus hours later. For the UK market we can supply live B.plicatilis starter cultures at different salinities for different applications.
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present. Right from resting cysts to adult rotifers the behaviour, feeding and breeding condition of a culture can be observed. Once the rotifer culture has been transferred to a larger vessel, a simple torch can often be used to illuminate and monitor culture densities.
Rotifer management and harvesting
Under optimal conditions rotifer cultures breed asexually with daughter cells produced.