Killifish are generally peaceful by nature and can get along well in community tanks with other small or non-aggressive fish. The males can however, be aggressive towards each other, so it's best to keep just one male per killifish species per aquarium, and to avoid keeping species which look similar. Any number of females will be happy together.
Killifish prefer a well-planted tank with lots of hiding places, and you should make sure that the hood is secure, as many of them like to jump. They're happiest in fairly shallow water with some floating plants to obscure the surface.
Killifish prefer live food, and will take most kins which are small enough for them to eat, including daphnia, river worms and small crustaceans. They enjoy live insects, but you should not be tempted to capture these from around your home or garden, as this risks introducing toxins and disease to the aquarium. Most species can be persuaded to accept flakes, though for best results you should supply them with a varied diet.
Types of KillifishThere are over seven hundred different species of killifish, some of which are endangered and many of which are difficult to keep in the aquarium. Some of the best aquarium choices are as follows:
- Lyretail Killifish - Among the most popular and long-lived killifish, these elegant little fish prefer slightly acidic water and subdued lighting. They can be very shy and take time to feel safe enough to feed.
- Medaka - These Japanese killifish are available in shades of white, yellow, gold and glow-in-the-dark green. They are famous for being the first vertebrates ever to breed successfully whilst orbiting around the Earth.
- Bluefin Notho Killifish -These very short-lived but hardy little fish are particularly prolific breeders. They are available in several colour varieties.
- Rainbow Killifish -With distinctive bright red colouration, these are among the largest species of killifish and are comparatively easy to maintain in the aquarium.
- Ceylon Killifish -Larger and hardier than most of their kin, these fish can also be more aggressive, but will be calmer if given plenty of hiding places.
- Striped Killifish -Comparatively long-lived, these peaceful fish prefer cooler water. They are particularly active and fond of jumping.