Moina

Moina


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Moina
By: Roger Winter

Moina is also known in the UK as Japanese Daphina and in the USA as Russian Daphina. There are in fact several species of Daphina and Moina is a very close relative but is much smaller. Another species is Bosmina and indeed many Moina cultures are in fact Bosmina cultures, however as both are the same to cultivate and eagerly accepted by all species of tropical fish it will not matter which species you have.

The main advantages of Moina is that it can be cultivated all year round in relatively small containers. The young are in fact smaller than newly hatched brine shrimp and of course being freshwater crustaceans they will live in the aquarium until they are eaten.

Cultivation is simple, simply obtain a starter culture of Moina. The container can be any non toxic vessel of a minimum of about 1 gallons / 4 litres. Moina do seem to prefer a layer of mulm on the bottom this can be either mulm from an aquarium or old well matured peat moss. Water should be neutral or alkaline, clean and clear. Moina do not seem to mind water drawn straight from the tap. Another other requirement is no plant life, I do not know why this is as they feed on decomposing organic matter but any plants growing or a large quantity of thread algae and the Moina either disappear or production is severely reduced. The final requirement is good strong light as again production is reduced or ceases in poor light. Temperature does not seem so critical and anywhere between 65 to 75oF 18 to 24oC will give good results and even lower temperatures do not slow down production that much.

Moina feed on bacteria and infusoria and the culture must be fed. Various concoctions are used by aquarists. Moina are cultivated commercially by fish farms (see Sinagpore Fancy Guppy Culture Web pages - follow links from the Fancy Guppy Association web site) and some aquarists use a scaled down version of their method by feeding a diluted manure concentrate. Sheep manure or rabbit droppings can be used to make the concentrate, yeast is also used but is expensive. Dried milk, rotting lettuce and the liquid from fermenting seed crops are also suitable. I personally use a liquor made from Gram flour as used to make onion bargees and available from any Indian food shop. I make up the liquor as follows - Mix four tablespoons of gram flour in a pint of water (1/2 litre) and bottle. The mixture can be used straight away and will ferment during the period it is used. Feeding consists of adding sufficient liquor to just cloud the water, to much and the Moina will not be able to clear it all and the water will foul to little and production will be reduced. The quantity is trial and error but you soon learn to judge the right amount. Dont worry if you do foul the culture just aerate the water until it clears and the culture should restart from the eggs in the mulm. The flour itself can just be scattered on the surface if preferred and will produce just as good results.

Moina reproduce both by live birth and by eggs that sink into the mulm. These eggs rest during adverse conditions and hatch when the conditions are suitable into females which hold the eggs within their brood pouch until they develop into females. This takes 7 -10 days and continues until adverse conditions such as food shortage or low temperature cause them to start to develop males. These males then mate and fertilise the females which then produce the resting eggs (ephippa) and the whole cycle starts all over again. This cycle produces what are known as pulses with periods of the water absolutely teeming with moina and hardly any at another time. This happens even in the small containers and the fleas should be regularly but sensibly harvested to reduce this to a minimum. Take out to many out and reproduction slows down until a healthy female population is built up again, to few and the food is exhausted and resting eggs are produced instead of young females. No matter how careful you are this is bound to happen so do not worry as the culture will soon pulse again. The culture can be kept going indefinitely. I have had a 8 x 8 x 10 inch high (20 x 20 x 25mm) all glass tank on my kitchen window sill for the last five years and it is still producing enough fleas to feed from one to three tanks a day on three or four days a week. I have also used plastic bowls and other plastic containers with good results to boost production when required by taking a starter culture from the tank and maintaining several thriving cultures. The Moina can be removed by netting with a fine mesh net or siphoning or even by syringe or meat baster. Livebearer fry can handle adult Moina but if very small fleas are required to feed egglaying fry then graded nets or meshes can be used to separate the fleas by size.

Obtaining a starter culture can be either from another aquarist who is maintaining one, likely candidates being killie keepers or avid breeders. I cannot recall ever seeing them offered commercially but it is quite easy to start your own by obtaining either daphina from a pond or purchasing a bag from your local aquarium shop. These will normally contain some Moina as well as the daphina. Pour them through a fine mesh net and retain only those that pass through the net and culture as above. Normal daphina do not take to well to this culture method in small containers and will normally not reproduce in quantity, by observing the culture and re sieving if necessary you will soon have a pure culture.

With Permission from
Viviparous

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