Breeding Rainbowfish and Blue-eyes

Rainbow fish spawn readily and are normally very productive. The catch is the tiny fry that are difficult to feed. Very small foods are needed for the initial days and this flaws most people.

I have used four techniques to counter this. I will deal with each beginning with the most effective method I employ. Firstly I will deal with spawning the fish.

It is vital to select healthy vibrant fish of good size and colour. The breeding tank best be of neutral pH and clean soft to medium hard water. The temperature should be about 26C and the tank should be at least 45 cm long for the medium size fish (6-9 cm). The spawning medium can vary as long as it is fine enough to catch eggs and hide them if needed. I use either Java moss or acrylic yawn mops. A sponge filter is a good idea. The pair or small group (in which case you would need a larger tank) can be added in the evening. Spawning will start at first light. For best results the females could of been conditioned for a week prior to spawning. The 'bows can jump so a hood or cover is needed. It takes between 7 and 14 days for the eggs to hatch depending on the species. When the fry hatch they hug the surface and retain this habit till about a month old. Because of this trait feeding them is a problem as they will not consume foods that sink too fast.

Late last year I received a small bottle of Baby Star II. This food consists of 50-100 micron (10-6 m) beads of emulsified nutrients. It is also known as Golden Pearls and sold by Brineshrimp Direct. This food sinks however which means the food will be out of reach for the surface hugging fry in a short time. To over come this I would dilution a drop or two in some tank water and then inject the emulsion into the stream of the sponge filter outlet or current of an airstone. This enables the emulsified beads to stay suspended for longer. The baby rainbows learn to accept this very quickly and grow well on it. Using this technique a friend has been able to raise even threadfin rainbows (Iriatherina werneri). Baby Star is much better than Liquifry and is available in six sizes (I-VI) and is designed to be a total substitute for baby brine shrimp.

Another good food is the powdered flake foods such as TetraMin Baby Fish Food "E". This powderred food floats on the surface and the baby bows take is immediately. When using Baby Star I feed both it and the powderred flake at the same time for a week or more. After a two weeks all the fry can take baby brine shrimp or other small foods. I have also used Mike Reed's No-BS fry foods with great sucess. I would recommend it above TetreMin "E".

Green water is the old standby but one iether uses too much: fouling the tank; or too little: starving the fry. My standard has always been to add 1 litre of culture per 9 litres of tank water in a 1:9 dilution. I would take 2 L out of the tank, add the green water and then 1 L of fresh water each day. I have found this to work well. I will often combine this and the above two methods to obtain the best results.

The last method, Liquifry, I have found to be ineffective. I would apply the liquid four days prior to the eggs hatching but as I would be expecting a staggered hatch I would have to keep adding with the result that large, frequent water changes are needed. Unless very few fry hatch the amount of microorganisms generated by the Liquifry is inadequate for all the fry.

To promote the growth of the fry frequent water changes are needed (20% each day) and preferably the fry should be kept in Calcium and Magnessium rich water. Some people have observed that the sex ratios can be manipulated with the water chemistry. I have not explored this and so far not had any problems with skewed sex ratios.

Breeding blue-eyes is very similar. The fish will readily spawn on mops or plants and generally don't molest the fry. The fry are larger than those of rainbowfish and normally can take baby brine shrimp on hatching. Microworms and vinegar eels are also good food. The fry of Ps. cyanodorsalis needs green water and infusoria for the first fed days. 

Blue-eye eggs can be treated very much like the eggs of non-annual killifish. They can be picked from mops and the development of the eggs can be delayed by placing the eggs in damp peat or in a salt solution (3 tsp/gallon). Using such tricks the eggs can be shipped all over the world.

Last updated 1.10.06