Fish, Tanks and Ponds


Fish, Tanks and Ponds
A comprehensive guide to fish

Breeding Nothobranchius

Nothobranchius killifish
Nothobranchius killifish

Introduction

These amazingly coloured fish are found in small pools and ditches across Eastern and South Africa in countries such as Tanzania, Mozambique, Kenya and South Africa. As many people know, this part of Africa undergoes an annual dry season. This means all the various pools and ditches where these fish are found will dry up completely.

In order for the species to survive another generation, they must leave their eggs in the pool under the protection of the muddy substrate. When the rains come again, the pools will refill with water and the eggs will hatch. Then the cycle will start again. For this reason, Nothobranchius are known as Annual killifish.

The annual cycle means that Nothos have a reasonably short lifespan, this will vary depending on the length of the wet and dry seasons in the particular area where a fish is found. In captivity, most fish (depending on species) will live for about 8 – 14 months. As a result of their short lifespan, the fish need to grow quickly to become sexually mature and lay eggs before the next dry season comes. For many species of Notho, they will be sexable at 6 weeks old and will begin spawning as soon as 8 weeks.

Maintenance

I use 12x8x8 tanks to breed pairs, trios and small groups of fish. The tanks are bare apart from a small air powered sponge filter and a spawning container. Many killifish breeders don’t use any type of filtration and just put a gently bubbling open airline in the tank. I chose to include the filters because they allow me to use slightly higher stocking densities when rearing young and because they act as a safety net incase a water change gets missed.

Most Nothos are found in a close to neutral pH but they are very adaptable in captivity. I use standard tap water which has a pH of about 8 and hard. This is said to help prevent an attack of Velvet (which Nothos are particularly prone to). Many also add a small amount of salt to the water as an extra precaution against this disease but I have never done so.

 The ideal temperature range is about 21 - 25°C. Lighting isn’t very important and it will make no difference to the fish whether they’re lit or not. I like to do weekly water changes of 30 – 40%. Most Nothos aren’t too picky when it comes to food although they may take a little time to adjust to certain foods (ie. Flake). I feed my fish twice a day, a standard tropical flake food in the morning and frozen food such as bloodworm, brine shrimp, black and white mosquito larvae and daphnia in the evening. This is supplemented with freshly hatched artemia.

Breeding

As said above, Nothos lay their eggs in the muddy substrate at the bottom of their pool or ditch. In the aquarium, using real mud just isn’t feasible, so a good substitute is peat. Any brand of peat is fine as long as it doesn’t contain any fertilisers or additives. I use Irish Moss peat which can be bought in large packs for a very good price.

To prepare the peat for use in the tank all you need to do is put a load of the stuff in a bucket of water and leave it. After 2 or 3 days the material will begin to sink, the sunken material is what you will be using. A handful of peat is then put into a spawning container. I use small margarine tubs for this purpose. The layer of peat only needs to be about 1cm thick. To get this in the tank without losing all the peat you have to be very careful.

I fill the tub right to the top with tank water and put the peat in. I then leave this on top of the tank for about half an hour or so to let the peat settle. Then lower the container very slowly into the tank. It doesn’t matter if some of the peat comes out.

As with most fish, it is best to condition the sexes separately prior to a breeding attempt. A week should be long enough for the female to fill with eggs and build up her strength. Once introduced to the breeding tank, the male will probably start displaying almost immediately.

The spawning involves the male driving the female down towards the peat and wrapping his dorsal fin over the top of her. Both fish will vibrate for a couple of seconds releasing eggs and sperm.

Glossary

 

References