Moina macropoda (by Peter Brown BKA 484)

Introduction

In the UK Moina is often referred to as Japanese Daphnia and in the USA Russian Red Daphnia. It is closely related to Daphnia species but is much smaller. When they are newly hatched, they are about 0.4 mm with males eventually reaching around 1.13 mm and females 1.65 mm. Moina have one of the highest protein contents of all cultured live foods. They are rich in vitamins A and D and depending on their food source small amounts of vitamins B and C. They can survive temperatures between 4-35 C but I find that a temperature of 24-26 C is ideal. Moina reproduce by live birth or eggs which drop into the bottom sediment. If the female has not been fertilized, she will drop eggs in a special pouch which hatch immediately and develop as females (parthenogenic reproduction). Every 3-5 days a female will produce 20 young, in a further 3-5 days the mother and young will produce offspring! This cycle continues until adverse conditions occur (overfeeding, underfeeding, overcrowding, poor lighting etc). Now, some of the hatching eggs will develop into males. These will mate with the females and cause them to lay resting eggs. These are protected in thick resistant brood pouches which can survive drought and be spread over wide areas. When conditions are suitable, these will hatch as females and the cycle will repeat.

 

I first became interested in Moina in 1981. Hans van Es contributed an interesting article on culturing it in December’s Killi-News and offered to obtain kits for interested members. Several friends began culturing Moina with reasonable success and I obtained a culture. It soon became apparent that a healthy productive culture one day could crash and die out days later. Eventually Moina seemed to disappear in the BKA and I had to return to weekly daphnia gathering trips …

Searching the internet a couple of years ago I discovered Green Water Farm products in Thailand (https://greenwaterfarmthailand.com). Among other things, they were selling Moina eggs with well detailed raising instructions. I ordered some and the eggs arrived quickly, with well tracked postage in two small, plastic capsules. I hatched ½ of one of the capsules in a 2cm depth of mature aquarium water in a small, well lit plastic tank. The young hatched in a couple of days and were smaller than newly hatched brine shrimps. I fed these on the weak solution of bakers yeast suggested in the instructions and they thrived. In a short space of time I was able to set up several culture jars adding a couple ofsmall Ramshorn snails to each to clean up settled out yeast. I fed enough yeast solution, twice a day to just ‘tint’ the water. Once a week each jar was poured through a brine shrimp net and replaced together with mature aquarium water. This always resulted in the release of lots of young. Occasionally a jar would fail, but having several ‘back ups’ overcame this problem. In addition to clearing up uneaten food the snail droppings contributed infusoria and became covered in algae which helped to keep the water healthy.

A couple of years on I feel reasonably confident in my methods. I like to keep a couple of large jars going, but tend to use 3 litre Hagen plastic tanks for culturing. These are half filled with mature aquarium water. I keep them at the top of the fish room close to the lights (10-12 hours) where they are kept at 24-26C. The feeding solution is made up by dissolving 1 level teaspoon of dried baker’s yeast in 600 ml of mature water. I feed 15ml of this to each plastic tank twice a day as the water clears. It is important to feed from the cultures regularly as this encourages the cycle prevents overcrowding which can lead to the sudden collapse of a culture. The Face Book Group – ‘Live Food Cultures For Aquariums’ has a wealth of interesting information relating to Moina and ideas for larger scale production. I would urge anyone looking for a clean, convenient healthy live-food to experiment with Moina, my Nothos., from fry to adults all love it, the range of sizes always available really helps to move them on.