The questions to ask a fish shop before getting a fork-tail rainbowfish revolve around energy: this species is a fast, surface-loving schooler that jumps, races, and breeds readily, so your conversation with the shop should cover lids, group size, and swimming room. Fork-tails are among the hardier rainbowfish, which makes the shop's husbandry answers — not the fish's toughness — the main thing you are evaluating.
Will these fish jump, and what lid do I actually need?
Fork-tail rainbowfish leap when startled, during courtship, and sometimes for no visible reason at all, so ask the shop directly whether its stock has been jumping and what cover its own tanks use. A tight-fitting lid with gaps sealed around filter pipes and cables is the honest answer; an open-top rimless tank, however stylish, will lose fork-tails onto the floor. Ask whether the shop sells or can order a suitable cover for your tank if yours has cut-outs. This question also reveals the shop's candor — a retailer who mentions jumping before you ask is one who has watched customers learn the lesson the hard way and would rather warn you first.
What group size and sex mix should I start with?
Fork-tail rainbowfish settle and spawn best in a proper school, so ask the shop for a group of eight or more with both sexes represented, and have staff point out the differences — males carry brighter yellow fin edges and a more intense blue eye. In a balanced group the males display and chase briefly without exhausting any one female, and the whole school uses the length of the tank. Ask whether the shop's current stock is one batch or several mixed together, and whether more of the same line arrive regularly if you want to grow the school later. A group bought together from one healthy system quarantines and settles as a unit, which keeps the first month simple.
What water are yours raised in, and how big do they get?
Fork-tails tolerate a wider range than many rainbowfish, but asking what temperature and hardness the shop keeps them in still prevents an avoidable shock on day one. Many shop systems run them in moderately hard, neutral-to-alkaline water, and locally bred stock raised in water like yours will barely notice the move. Ask about adult size, too — fork-tails stay small, around two inches, but their activity level makes them feel like bigger fish, so tank length matters more than raw volume. If the shop has a mature display group, look at how the adults use the upper half of the tank; that is the layer your aquascape should leave open and planted around the edges.
What are they eating, and will they breed in my tank?
Fork-tail rainbowfish take small floating and slow-sinking foods eagerly, so ask what the shop feeds and watch a feeding if you can — a school that charges the surface together is a healthy one. Ask the follow-up most shops expect from rainbowfish keepers: will they breed at home? Fork-tails scatter eggs among fine plants and spawning mops, and in a planted tank a few fry often survive without any effort from you. Knowing that in advance lets you decide whether to add plants that shelter fry or tankmates that will politely eat the eggs, rather than being surprised either way.
Energetic fish reward a shop that plans for the energy instead of apologizing for it, and the Pet Services Directory in KinsLe lets you compare local fish shops so your fork-tail school comes from people who keep lids on and groups together.