Which killifish are best to start with?

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The three most common non-annual killifish you’ll find in the trade are Fundulopanchax gardneri, Aplocheilus lineatus, and Jordanella floridae...

Q) I’d like to have a go at keeping non-annual killifish and I wondered if you could recommend two or three reasonably easy ‘starter’ species. I live in a medium-hard water area, so would need to avoid the very acid-loving ones, at least until I get some experience. I’ve been keeping fish for three years, but this will be the first time I’ve tried a specialist fish of any kind.

MANDY EARL, VIA EMAIL

A) NEALE SAYS: Probably the three most common non-annual killifish you’ll find in the trade are Fundulopanchax gardneri, Aplocheilus lineatus, and Jordanella floridae. In their way, they’re quite representative of three basic sorts of killifish: the non-annual African pool-dwellers; the Asian and Madagascan panchax; and the pupfishes, mostly found in North America, respectively.

The Steel Blue Killifish, Fundulopanchax gardneri, is a charming fish that has been bred into a wide range of artificial forms, including the very popular ‘gold’. It’s relatively small (up to around 5cm long) but, like most killifish, is quite aggressive for its size. Males are particularly feisty, but given space, mixed-sex groups are viable, ideally with females outnumbering males. People often keep small groups in tanks upwards of 45 l, with gentle (ideally, air-powered) filtration to mimic their swampy habitats in the wild.

They are classic egg-scatterers when it comes to breeding, with pairs laying sticky eggs among fluffy plants or spawning mops. Moderately soft water is preferred, but you might get away with water that isn’t too hard, especially if you could mix your tapwater with rainwater or RO water. Aim for 2-12°dGH and around pH 7, and you should be fine. It will do best around 22-24°C — if kept too warm,nyou’ll find it quite short lived. In the wild, it’s likely this species can switch between being an annual or a non-annual species depending on its environment, but even in ideal conditions, it isn’t going to live more than a couple of years, so breeding is important if you want to enjoy the species in the longer term. Keep the tank well covered because they are jumpy! Floating plants will help, but obviously a hood will be essential.

The Striped Panchax, Aplocheilus lineatus, has been a hobby staple for years, and an artificial variety called the Golden Wonder Killifish, turns up in most aquarium shops on a regular basis. It’s a fairly big species, at 8-10cm long when fully grown, and because it has a very broad distribution in the wild, handles a wide range of water chemistry values, from fairly soft and acidic through to slightly brackish. As such, it’s an obvious pick for someone who doesn’t want to get too bogged down in playing around with water chemistry.

On the other hand, these big, jumpy predators will consume small fish up to the size of male guppies. So, while they’re among the better choices for community tanks, they’re not completely trouble-free. They’re not fussy eaters, and the tank-bred specimens in the trade will eat everything, including flakes and pellets. Like so many other killifish, you don’t want to keep these fish too warm, with around 24°C being ideal.

Among the pupfish, the one you’ll see in many aquarium shops is the Florida Flagfish, Jordanella floridae. Unlike the killifish mentioned so far, but typical for pupfishes, this species is omnivorous, with a definite taste for green foods, including algae. In fact, in the wild pupfishes are best described as detritivores, pecking away at the rocks and silt in their environment. Under aquarium conditions, the species is very accommodating, consuming flake foods alongside algae and softened vegetables. Soft-leaved plants are likely to be nibbled at, too.

Wild fish inhabit everything from swampy pools to brackish streams, so hard water isn’t going to be a problem, but as subtropical fish, I’d aim for 22°C in summer, and down to around 18°C in winter. Kept this way, they should live two or three years, which will give you ample time to get them breeding.

Unlike the egg-scatterers covered so far, this species extends an almost cichlid-like degree of care to its spawn. Males defend small territories, driving off any potential egg-predators (including the females) but once the eggs have hatched, they show no further interest, even to the point of consuming any free-swimming fry they come across.

Rockets and Lyretails

When looking for killifish, you might also come across Epiplatys species, of which the most famous is perhaps the Rocket Panchax, Epiplatys annulatus, and Aphyosemion species, such as the popular Lyretail Killifi sh, Aphyosemion australe. Their care is broadly similar to that of Fundulopanchax gardneri, but they may be a little more choosy in terms of water chemistry, aquarium size, and social behaviour.

Aphanius mento is a West Asian pupfish species from places like Turkey and Iran, where summers can be very hot but winters much colder. As such, the species has a broad temperature tolerance. Warmer summers will encourage breeding, in which case you could add a heater to bring the tank up to 22°C or so, but in winter, even 10°C isn’t going to cause them harm. They need plenty of space and hard water. The males are gorgeous — midnight blue with iridescent spots — but very aggressive, and unless the tank is huge, keeping two males together usually ends badly, so aim for two or more females alongside a single male.