3,895 answers about fish & aquatics
A healthy aquarium is a balanced one — water chemistry, filtration, stocking and feeding all work together, and most fish problems start with the water. This page gathers the fish and aquatics library of KinsLe Answers in one place, organized by topic for freshwater and saltwater keepers alike. Every answer is original, written by KinsLe, and tied to a real KinsLe feature.
562 answers in Choosing & Adopting — page 16 of 24
For a first tank, freshwater is the right call for most people — and it is not a consolation prize. Freshwater setups forgive beginner mistakes, need no mixing or salinity checks, and make a missed water change a problem rather than a disaster, while saltwater adds exact salt levels, evaporation top-offs with purified…
Usually not — zebra danios are the classic exception. They come from cool, fast streams in the Himalayan region and are genuinely comfortable between about 64 and 75 degrees Fahrenheit, so a normal home's room temperature sits right in their range and many danio tanks run unheated for years. Add a heater only if your…
Generally yes, though swordtails are among the hardier tropical fish. They come from the rivers of Mexico and Central America and do best between about 72 and 82 degrees Fahrenheit, and while a warm, steady room can hold the lower end of that range, most homes let a tank sag below it at night and in winter, when…
Yes. Siamese algae eaters come from warm, flowing rivers in Thailand and the Malay Peninsula and do best between about 75 and 79 degrees Fahrenheit, a range an unheated tank only reaches in a warm summer, and cool water throttles down the constant grazing this fish is valued for. Because they are strong jumpers as…
Yes. Pearl gouramis are large, graceful labyrinth fish from the warm swamps and slow rivers of Malaysia and Indonesia, and they want water between about 77 and 82 degrees Fahrenheit — far warmer than an unheated tank in a normal home, where their pearly spotting fades and males lose the orange throat that makes the…
Yes — and for otocinclus, stability matters even more than the exact number. These tiny South American catfish do best between about 73 and 79 degrees Fahrenheit and are famously sensitive to change of any kind, so an unheated tank drifting with the room's day-night rhythm subjects them to exactly the slow swings they…
It depends on your room. Mystery snails tolerate a wide span, roughly the high 60s to low 80s Fahrenheit, so a warm, steady room can keep them perfectly well without a heater — but warmth buys activity, since snails at the upper end cruise, graze, and grow steadily while cooled ones slow down and may sit closed in…
Yes. Kuhli loaches come from warm, leaf-littered streams in Southeast Asia and do best between about 75 and 79 degrees Fahrenheit, and as bottom dwellers they live in the coolest layer of the tank, right against the glass, where unheated water leaves them hiding almost constantly and foraging half-heartedly. Place the…
Yes, in nearly every home. Harlequin rasboras come from warm peat swamps and slow streams in Southeast Asia and do best between about 73 and 79 degrees Fahrenheit, while an unheated tank usually sits in the high 60s, where a school loses its coppery shine and feeds without enthusiasm. Heat the tank during the cycle…
Yes, without much debate. Dwarf gouramis come from the warm, still, plant-choked waters of South Asia and are happiest between about 77 and 82 degrees Fahrenheit, well above what an unheated tank holds in most homes, and cool water leaves them listless and vulnerable to the health troubles this species is known for.…
Usually not. Cherry shrimp thrive at ordinary room temperature, roughly the high 60s to mid 70s Fahrenheit, and most successful home colonies run unheated. A heater earns its place only if the room regularly drops into the low 60s or swings sharply between day and night, because sudden change bothers shrimp far more…
Yes. Cherry barbs come from warm, shaded streams in Sri Lanka and do best in water held between about 73 and 79 degrees Fahrenheit, warmer than most living rooms keep a tank, and without a heater they lose color, school less tightly, and grow sluggish and more prone to illness. Set the heater before the fish arrive…
Yes, in most homes a bristlenose pleco needs a heater, because it is a tropical catfish that stays healthiest in steady water in the mid-seventies to low eighties Fahrenheit. An unheated tank may feel fine on a summer afternoon yet dip several degrees on a winter night, and repeated dips weaken a pleco's digestion and…
Yes, zebra danios and cherry barbs pair beautifully, because both are hardy, peaceful schooling fish that enjoy the cooler end of the tropical range and constant gentle activity. Keep six or more of each so both schools behave naturally, and choose a long tank of twenty gallons or more to honour the danios' love of…
Yes, swordtails and mollies are a classic livebearer pairing that shares warm, hard water and a busy, peaceful temperament. Swordtail males can be pushy with each other, so keep one male to several females and give the group thirty gallons or more, since both species grow to a solid size. Both breed readily and will…
Yes, with one watch-out: Siamese algae eaters are lively, hardworking fish that generally leave angelfish alone, but an underfed adult may latch onto a slow angel's flank to graze its slime coat. Keep the algae eater genuinely fed with algae wafers and vegetables so the angelfish never looks like a meal, and give the…
Yes, pearl gouramis and angelfish can share a tank, provided it is large and tall enough for both — forty gallons or more, with height for the angelfish's deep body and finnage. Both are calm, warm-water fish that cruise the middle layers, and pearls are among the hardiest, least timid gouramis. Add plants and…
Yes, otocinclus and cherry shrimp are one of the safest pairings in the nano hobby, because otos are gentle algae eaters with tiny mouths that leave even baby shrimp essentially alone. Add both only to a mature tank with established biofilm and algae, since each species grazes that growth all day. Keep otos in a group…
Yes, neon tetras and harlequin rasboras are an excellent school-fish pairing, because both are peaceful, stay small, and favour the same soft, warm, slightly acidic water. Keep at least six, and ideally eight to ten, of each species — half-groups of schoolers school poorly and hide. A planted twenty-gallon long tank…
Yes, guppies and platies are one of the easiest livebearer combinations, since both are peaceful, stay small, and thrive in the same warm, hard water. Keep two or three females for each male guppy so no single female is courted constantly, and add floating plants or dense corners where fry of both species can shelter.…
Yes, guppies and mollies mix well, because both are livebearers that like the same warm, hard, mineral-rich water and neither bothers the other. Stock two or three females for every male of each species so the males' constant courtship is spread out, and choose a tank of twenty gallons or more since mollies grow…
No, goldfish and neon tetras are among the least compatible pairings in the hobby. Neons are tiny tropical fish that need warm, soft, acidic water, while goldfish need cool water and grow large enough to eat a neon in one bite. Even a juvenile goldfish will harass and out-compete them long before predation starts, so…
No, goldfish and guppies should not share a tank, because they want different water and the goldfish will eventually treat the guppies as food. Goldfish thrive in cool, unheated water and grow large enough to swallow any small fish that fits in the mouth, while guppies need steady tropical warmth to stay healthy.…
Yes, dwarf gouramis and cherry barbs are one of the calmer beginner pairings, because both are peaceful fish that occupy a planted tank without chasing or fin-nipping. Give the gourami the top and middle water under gentle flow and some floating cover, and keep the barbs in a proper shoal of at least six so their…
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