Ask about pairs, groups, and origins
Ask whether a shop's clown killifish are tank-bred and whether you can buy a pair or a small group rather than a single fish. This tiny killifish lives socially in the wild, and a lone fish in a bare tank is usually a stressed fish. Tank-bred stock tends to accept a wider range of foods and settles faster than wild imports. Ask how long the fish have been in store and look for the bold black-and-yellow banding and, on males, the lyre-shaped tail with its colourful extensions. A shop that keeps clown killifish in a planted display rather than a bare cell is showing you it understands the species.
Ask what the killifish are eating
Ask what the clown killifish are fed in the shop, because feeding is the make-or-break detail for this species. Their mouths are very small and upturned for taking insects from the surface, and many individuals ignore dry food entirely at first. Ask whether the shop uses live or frozen baby foods, whether the fish take any prepared diet, and ask to watch a feed so you can see the fish rise and eat confidently. Ask how often they are fed, since small surface hunters do better on little and often. If the shop cannot tell you what its killifish eat, buy elsewhere.
Ask about lids, tank size, and setup
Ask the shop to be specific about the lid, because clown killifish are exceptional jumpers that find gaps around cables and corners. A good answer covers a close-fitting cover with no open slots, not just a general warning. Ask what tank size the shop keeps them in and what layout it recommends, since a modest aquarium with dense planting and floating cover suits them better than a large open one. Ask about tankmates as well, because anything big enough to swallow a clown killifish eventually will, and fast feeders leave them hungry. Their small size makes planning the community a shop conversation worth having.
Ask about their water conditions
Ask what temperature and water chemistry the shop keeps its clown killifish in. They come from slow, soft, slightly acidic forest streams in West Africa and appreciate warm, gentle water without strong flow blasting the surface they live under. Ask whether the shop's water is close to your home supply, and how it acclimates new arrivals, because delicate surface fish suffer when moved abruptly between very different conditions. Ask about filtration outflow in their sale tank, since a calm surface is part of keeping this species feeding well. Note the values the shop gives you so your setup mirrors them from day one.
Ask about sexing and keeping notes
Ask the shop to help you sex the clown killifish you choose, because keeping several males in a small tank without enough females or cover can lead to constant sparring. Males carry the dramatic tail extensions, while females are rounder with plainer fins, and a good shop will pick a balanced mix without rushing you. Ask about the fish's background one last time before paying: origin, foods, water, and how long they have settled. Those four facts form the care sheet the fish arrives with, and through KinsLe the Pet Passport keeps that killifish information together in one portable packet, ready for a vet visit, a move, or a handoff.