Get started with killifish


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  This fish packs an incredible amount of colour into a small body.  This fish packs an incredible amount of colour into a small body.
Get started with killifish

This fish packs an incredible amount of colour into a small body.

If you’re tempted by killies but not sure which species to start with, you won’t go far wrong with Aphyosemion striatum, says Steve Davidson.


Fish Factfile
Common name: Red striped killifish, Striatum killifish
Scientific name: Aphyosemion striatum (Aff-e-o-see-me-on stry-ar-tum).
Size: 5–6cm/2–2.2in.
Lifespan: Around two years.
Ease of keeping: No problem for competent fishkeepers and a perfect introduction to killifish. 
Feeding: Will accept some flake food, although as with all killifish they much prefer live foods. Frozen mini bloodworm is taken with relish. 
Availability and cost: Sometimes found in shops, on internet auction sites, and certainly through members of the British Killifish Association. Price around £12–16 a pair in shops, but less if bought from a  dedicated hobbyist/breeder.

  Males Striatum killies rival many marine fish in terms of colour.

Males Striatum killies rival many marine fish in terms of colour.

Every so often we come across a fish that stops us in our tracks. Perhaps it’s the shape of the fins — or, as with the Striatum killifish, it’s the colour. 

This stunning tooth-carp has colours that would rival the brightest marine fish, with shades of red, green, yellow and blue all packed into a slender body that is just 5–6cm/2–2.2in long. The colours are clearly defined, and similar to the vibrant punchy shades often found in a children’s playground. An added bonus with this little beauty is the ease with which it can be kept
and bred.

Aphyosemion striatum is native to Africa, found in Gabon and Equatorial Guinea. It inhabits mainly small streams and swampy areas within or bordering the rainforest and has been found in water that is quite shallow. When collectors have been looking for small Aphyosemion species in the rainforest, many have reported finding fish close to the bank. Where trees overhang this creates some shade and here the water temperature will be slightly lower — often around 20–23°C/68–73°F. Aphyosemion striatum falls within this temperature range.

  Female Striatum killies lack the intensity of the males' colours but are still attractive fish.  Female Striatum killies lack the intensity of the males' colours but are still attractive fish.

In the aquarium

This is the ideal species for the newcomer to killifish. It’s not too hard to obtain and is easy to feed as well as making a great breeding project — and then there’s all that colour! 

You don’t need a large aquarium to keep these fish — a pair or a trio (one male, two females) can be housed in a 30 x 20 x 20cm/12 x 8 x 8in tank. Ensure you have a tight fitting lid as many killifish are aquatic gymnasts, and may launch themselves out of the water and through a tiny gap. The water needs to fill around 70% of the tank and be around 23°C/73°F in temperature — a couple of degrees either side of this can have an effect on spawning activity. 

For many years I used mains water with the obligatory water treatment to render it safe for my fish, but a couple of years ago I switched to using 100% rainwater for my killifish and guppies. It has a pretty consistent pH of 7 but anywhere between the range of pH 6.6–7.2 should be fine for these fish. In the past it was common practice to use some pre-soaked Irish moss peat as a substrate for killifish, but if your water is pH 7 or below the peat could make your water too acid over time. Nowadays many killie keepers use pre-soaked coir as it is considered inert, so should not alter your water chemistry. An airline bubbling away quietly and a spawning mop or two made of a synthetic wool is all that is required. You don’t need real plants although they do enhance the appearance of the tank. 

Some killifish species can be a bit reluctant when it comes to spawning, but A. striatum is a species that should present few (if any) problems for a reasonably competent aquarist.

Storing the eggs

The eggs of these fish are fairly small, but when the adults are conditioned well they will be laid in profusion. There is always some debate among killifish-keepers as to the best way to store eggs. Some people say to put them in a small container, such as a well cleaned 500g margarine tub containing some of the parents’ tank water. Others, like myself, favour putting them on a small amount of damp peat in a small container with a lid. I use small plastic containers around 45mm in diameter with a lid attached by a small integral strap. I cut up computer address labels for attaching to the egg containers. These can then be used to record the species name, date collected, and number of eggs. 

The eggs take on average 16 days or so to hatch. I hatch eggs in small plastic containers made from a clear Tupperware type plastic, around 100 x 50 x 75mm (sold for craft purposes in stores such as The Range). 

  Developing  Aphyosemion  fry inside an egg.

Developing Aphyosemion fry inside an egg.

Rearing the fry

Fry are quite small on hatching and ideally should be fed newly hatched brine shrimp which is full of protein. A word of caution though, feed brine shrimp very sparingly. Any that is not eaten will die fairly quickly and foul the water. If this happens it’s very likely the fry will succumb to velvet. In my experience once this occurs with fry it’s fairly certain you will lose them, so exercise caution when feeding fry! Microworms that are kept in a Ready Brek type mixture can also be fed to the fry. A singular use of a child’s paintbrush is ideal for feeding these — just dip the brush into the worms so a few of them attach to the tip of the bristles and then swirl it in the tank.

With fry held in small containers you can monitor their progress. The relatively small amount of water will slowly evaporate within a fish room, so topping it up with similar water is required. I tend to decant off around 50% of the water into a cleaned out margarine tub, allowing me to see any small fry that have carried over. If you do not have the luxury of a space heated and dedicated fish room then you will need to find a way of keeping the fry container warm —floating it in the parents’ tank is an option, providing it won’t topple over. 

Growth will be slow as is the case for most Aphyosemion species. As soon as they reach around 8mm long I transfer them to a small tank somewhere in the region of 20 x 10 x 10cm/8 x 4 x 4in. This gives them more room to develop. I still change around 40–50% of the water at least once a week to keep things sweet. Changing a portion of the water also helps to maintain an even growth rate among the fry. If you can arrange for a very slow trickle of air via an airline and valve/clamp then this will prevent the water from skinning over. If this is not feasible then gently moving the water around with a clean finger will do the trick.

When fry reach 12-15mm in length you can consider moving them on to something like a 30 x 20 x 20cm/12 x 8 x 8in tank. This is big enough for them to grow on but still small enough to be able to monitor the fry. You should be able to spot any uneaten food in a tank of this size and remove it before problems unfold. Continue with feeding freshly hatched brine shrimp which can be supplemented with some very small Grindal worms as the fry grow.

You can of course leave the eggs to hatch within the parents’ tank. The plus is that fry hatching in tanks alongside their parents seem to grow a bit faster than when hatching and rearing them separately. But some fish will devour their fry, and larger fry will sometimes consume newly hatched individuals, although just today I have found some fry a few weeks old swimming happily alongside their parents.

After a few months you should end up with some fish whose colours approach or even rival that of marine fish.

Join the club!

Become a member of the British Killifish Association. Find out more at