Killifish UK: Types, Care & The Killis We Stock

Which killifish should you actually keep?

You've seen a photo of a killifish - probably a Nothobranchius blazing red and electric blue, or a Gardner's killi in steel-blue and gold - and now you're trying to work out whether you can keep one. Most guides make this harder than it needs to be: they either treat "killifish" as a single fish with one care sheet, or they dump two hundred species on you with no way to tell the easy ones from the projects. Both leave you stuck.

I'm Connor Boyle, and the coldwater and oddball fish are my corner of Tropical Fish Co. Killis are the species I get asked about most by people who've fallen for a picture and have no idea where to start. Here's the honest framing the trade rarely spells out: killifish aren't one fish - they're a whole family of small egg-layers split into two very different camps ^[1]. Get that split right and everything else falls into place; get it wrong and you'll be disappointed when a "delicate" fish dies on schedule.

This page is the conversation I'd have across the counter when someone asks "can I keep a killifish?" - what the types are, the all-important annual versus non-annual divide, which killis suit a community and which want a tank of their own, and exactly which ones we have in stock. It pairs with our water chemistry guide (killis are fussy about water) and our first tropical tank guide if you're still setting up.

One of our Gardner's killifish (Fundulopanchax gardneri) - a non-annual, beginner-friendly killi that lives 2-3 years and shows off the electric blue-and-gold most people picture when they think "killifish". Credit: Tropical Fish Co.

Fun facts - the stuff most UK killifish guides skip

Killifish hide some of the strangest biology in the freshwater hobby. These are the facts that actually change how you think about keeping them:

• One killi is the shortest-lived vertebrate we can breed. Nothobranchius furzeri, the turquoise killi, has a captive life of under three months - the shortest lifespan reliably documented for any back-boned animal ^[3][2]. That isn't fragility; it's an evolved race against a drying pool.
• Their eggs survive being dried out - on purpose. Annual killis lay eggs that go dormant encased in damp mud through an entire dry season, then hatch when the rains return ^[2]. It's why you can legitimately receive annual killifish "as eggs in the post" from breeders rather than as live fish.
• A pet-shop fish is now a serious laboratory animal. Because N. furzeri ages so fast and shows mammal-like ageing, it's become a model organism for ageing research - scientists even measure how water temperature and compounds like resveratrol shift its lifespan ^[3]. The fish in our tanks has a parallel life in gerontology labs.
• Lampeyes have headlights. The "lampeye" name comes from a brilliant iridescent blue-green ring over the top of the eye that catches the light like a tiny lamp - most striking on a shoal under gentle lighting. They're peaceful, social and one of the easiest killis to keep ^[4].
• The beginner killi is also one of the prettiest. Aphyosemion australe - the lyretail / Cape Lopez killi - is non-annual, lives in permanent streams, tolerates a wide range (pH 5.5-7.0, 21-32 °C) and is explicitly rated "ideal for aquarists new to killifishes" ^[4]. You don't have to earn your way up to a beautiful killi.

The killifish types we stock - compared

Here's the part that makes the decision easy. Killifish span several genera, and the practical differences come down to annual vs non-annual, water, and difficulty - so that's what the table compares. (Adult size is broadly similar - most are 3-6 cm - so I've kept the focus on what actually varies between groups.)

New to killis? Start at the top - a lampeye, an Aphyosemion australe, or a Gardner's. They're long-lived and forgiving. The Nothobranchius near the bottom are the dazzling annuals: stunning, but a short-lived, soft-water, species-tank project rather than a first fish.

Here are the killis we have in stock right now, listed so you can see the full range from easy non-annuals to the prized annual Nothobranchius:

Annual vs non-annual - the one thing to get right

Almost every killifish question comes back to this split, so it's worth a section of its own.

Annual killis evolved in temporary pools that dry out each year. The whole life cycle is compressed into a single wet season: hatch, grow fast, blaze with breeding colour, spawn into the mud, and die as the pool dries. The eggs then sit dormant in damp earth until the rains return and trigger a hatch ^[2]. In the aquarium this means three things: spectacular colour, a short life of roughly 3-12 months ^[5], and breeding that revolves around damp peat rather than plants. The Nothobranchius we stock - guentheri, rachovii, patrizii, eggersi - are all annuals.

Non-annual killis come from permanent streams and swamps. They live a normal small-fish span of 2-5 years, breed by scattering eggs among fine-leaved plants or spawning mops, and generally ask far less of you ^[4][5]. The Aphyosemion (australe, gardneri, hjersseni), the lampeyes and the panchax are all non-annuals.

Species tank or community?

This follows directly from the type:

• Lampeyes and panchax are the community-friendly killis. A shoal of lampeyes mixes happily with small rasboras, small tetras and peaceful bottom-dwellers in a calm planted tank.
• Nothobranchius and many Aphyosemion are best in a species tank. Males are territorial with each other, their soft-water needs are easily compromised by boisterous tank mates, and a species setup is also how you'll ever breed them ^[4].
• As a rule of thumb: lampeyes and panchax for a community; the fancy, jewel-coloured killis for a tank of their own.

Keeping killis well - water, feeding and tank mates

Day-to-day, killifish are not difficult fish - they're just specific. Get these right and most types look after themselves:

• Water: soft and slightly acidic is the theme - roughly pH 6.0-7.0 and soft hardness for most species, with lampeyes flexing a little higher to ~7.5 ^[1][4]. Our water chemistry guide covers how to get there from UK tap water; annual Nothobranchius in particular want genuinely soft water, so many keepers cut tap with RO or rainwater.
• Temperature: 22-26 °C suits the types we stock, with some Nothobranchius tolerating warmer ^[1]. Cooler is fine for many killis and can even lengthen an annual's life.
• Feeding: killis are carnivores and insectivores - lean on frozen and live foods (bloodworm, daphnia, brine shrimp, mosquito larvae). Many non-annuals also take quality flake or micro-pellet; annuals do best on meaty foods ^[4].
• Filtration & cover: gentle flow (a sponge filter is ideal) and floating plants for security suit these surface fish - and, again, a complete lid ^[7].

For tank mates, choose by type. The community-suitable killis pair well with small, peaceful nano fish, and a planted tank with cover keeps everyone calm:

• Water chemistry guide - the foundation for getting the soft, slightly acidic water killis want from British tap water.
• First tropical tank guide - if you're setting up your first tank, this is where to start before adding any killi.
• Killifish hub - the full shortlist of killis we have available, all in one place.

A closer look at an annual killi

One of our Nothobranchius eggersi blue - an annual killi from East Africa. This is the type that races through life in months and leaves drought-proof eggs in the substrate. Spectacular colour, but a soft-water, species-tank project rather than a beginner's first fish. Credit: Tropical Fish Co.

This is the fish that gives killifish their dazzling reputation - and their misleading "difficult" label. An eggersi or a rachovii isn't hard to feed or house; what's different is the life cycle. Kept in soft, slightly acidic water in a species tank, fed well on frozen and live foods, an annual Nothobranchius will reward you with colour that genuinely rivals a marine fish ^[5]. Just go in knowing it's an annual - a few vivid months, with breeding built around damp peat ^[2] - and you'll get exactly what this remarkable fish is meant to give.

A note on UK water before you buy: most British tap water away from the soft-water north and west is on the hard, alkaline side, which is the opposite of what killis want. For non-annuals like australe and Gardner's that's usually manageable, but for soft-water annuals you'll likely want to cut your tap with RO or rainwater - see our water chemistry guide for how to do it safely.

When your killifish arrive - acclimation for small, soft-water jumpers

Killis travel well for their size, but they're small, soft-water fish that don't like sudden swings - and the moment the bag opens is the moment a jumper looks for an exit. Our live-animal courier delivers in an insulated, oxygenated bag; your job is a calm, lidded handover. The killifish-specific protocol:

1. Receive in a quiet, dimly lit room and check the bag temperature before you do anything - don't unbox on a bright worktop.
2. Float the sealed bag for 20 minutes to equalise temperature.
3. Drip-acclimate for 30-45 minutes at 2-3 drops per second. Soft-water killis are sensitive to sudden pH and hardness shifts, so take the drip slowly ^[7].
4. Net the fish into the tank - never pour bag water in - and close the lid immediately. A freshly introduced killi is at its most likely to jump in the first hour.
5. Lights off for a few hours and no food for 24 hours. A new killi may hover near the surface or hide in the plants at first - normal settling, not illness.

Have the tank cycled, soft-watered and securely lidded before they arrive. For a shoaling lampeye, introduce the group together; for territorial species, give them planting and line-of-sight breaks so no single male dominates from day one.

Community - where UK killifish keepers talk

Killifish have one of the most dedicated followings in the hobby, and the UK is unusually well served:

• The British Killifish Association is the national club - and the single best resource for British killi keepers. It runs regional shows and egg/fish auctions, keeps breeders' records, and is how most enthusiasts obtain rarer annual species (often as eggs) ^[6]. If you catch the killi bug, this is where to go.
• Practical Fishkeeping has long covered the UK killi scene - including the BKA's milestone anniversaries and conventions - and is a reliable, British source for species features and husbandry.
• Seriously Fish has detailed, well-referenced species profiles for most killis you'll meet - the place to sanity-check a fish's water needs and annual/non-annual status before you buy ^[4].

A common thread across all of them: experienced killi keepers think in terms of the life cycle first. Learn whether your fish is an annual or a non-annual, give it soft water and a proper lid, and you'll fit right in.

Ready for more?

Now you know killifish are two hobbies in one - the easy, long-lived non-annuals and the dazzling, short-lived annuals - the choice comes down to which suits you. Pick the type, give it soft water and a tight lid, and you'll be keeping some of the most beautiful freshwater fish there are.

• Shop: Killifish · all tropical fish for sale
• Learn: Water chemistry guide · First tropical tank guide
• Compare: Tropical fish for sale UK · Cold water fish for sale

Every claim above is sourced - see the References block below. If you're torn between an easy non-annual and a dazzling annual, or you're not sure your water suits a Nothobranchius, ask us first. We'd rather match you to the right killi than sell you the rarest one.