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 18 of 24
Five gallons is the accepted minimum for a betta — enough water for a small heater and filter to hold stable tropical conditions, and enough room for the fish to patrol, build a bubble nest and choose where to rest. Ten gallons is easier still: the water changes more slowly, mistakes forgive more readily, and the…
Plan on at least a twenty-nine or thirty-gallon tank for angelfish, and choose a tall model — these are deep-bodied fish that use height as much as length. That floor suits a pair; a group of juveniles or a community built around angels is honestly a fifty-five-gallon conversation, because adults reach around six…
Design out the classics before the fish comes home: an uncycled tank that poisons him in week one, a bowl or tiny unheated box instead of a filtered five gallons or more, sharp plastic plants that shred long fins, a strong filter current he must fight all day, and no lid on a fish that jumps. Set the tank up, cycle it…
The setup is the loud cost; the running costs are the steady drip: electricity for lights, heater and filter running around the clock, water and conditioner at every change, liquid fertiliser and root tabs for the plants, and carbon dioxide refills if you inject gas. Add the quiet replacements — test-kit reagents,…
Build the tank's social ladder from the bottom up: peaceful, shy species go in first and get weeks to learn the caves and feeding spots, mid-level community fish follow, and the territorial fish arrives last, when every hiding place is already claimed and it must negotiate rather than conquer. Space additions at least…
Keep zebra danios in a school of at least six, and closer to eight or ten if the tank allows — the bigger the school, the more their sparring spreads out and the less any single fish gets chased. In twos and threes they turn nippy and stressed, and they may start worrying slower tankmates. Danios are surface-oriented…
Siamese algae eaters are schooling fish at heart, and a group of five or six is the reliable choice — in a proper group they graze together, squabble mildly among themselves, and leave other species alone. A lone fish works in a smaller tank but tends to be shyer and can get pushy with similar-looking tankmates as it…
Pearl gouramis do best as a small, calm group rather than alone or as a random pair: a trio of one male with two females works well, and in a larger tank a group of four to six spreads out any chasing and lets their shy side relax. Two males together can spar over territory, so if you want several males, give them a…
Keep neon tetras in a school of at least six, and choose ten or more whenever the tank allows, because their famous river of blue and red only forms when the group is big enough to feel safe in open water. Small groups in bare tanks stay near the plants, colours muted, while a double-figure school in a settled, mature…
Mystery snails get along with each other easily, so the number is set by food, space and waste rather than by temperament, and a rough working guide is one snail for every five gallons of a well-filtered tank. Two or more will explore, feed and pile into corners together without conflict, though a male and female pair…
Keep kuhli loaches in a group of at least six, and more if the tank floor allows, because a lone kuhli is a nearly invisible fish that hides all day and ventures out only to snatch food. In a group they drape over driftwood, sift the sand in loose company after lights dim and grow bold enough to rest in the open. Deep…
Keep harlequin rasboras in a school of at least six, and aim for eight to ten or more, because they are true schooling fish whose copper colour and tight formation only appear when the group feels secure. A trio will hug the plants and show you almost nothing of the species, while a larger school cruises the middle…
Keep guppies in a small group built around a ratio of one male to at least two females, with a trio as the minimum and six or more giving a livelier, more settled display. All-male groups can work in roomier tanks where no single fish is cornered, but mixed groups with too many males leave females harassed and…
Goldfish are social and do best with at least one companion, but the right number is set by adult size and waste rather than by how many fit today, so most home tanks suit two or three fancy goldfish at most. Slender single-tailed types grow long and powerful, belong in very large tanks or ponds, and should not be…
Keep corydoras in a group of at least six of the same species, with eight to twelve being better still, because these are shoaling catfish that rest, feed and travel in company. Different cory species in twos and threes often ignore each other rather than forming one happy mixed group, so one proper school of a single…
Keep cherry barbs in a group of at least six, and choose eight to ten if the tank allows, because lone or paired barbs turn shy, pale and reluctant to leave the planting. A mix with more females than males works best, since males colour up and display to each other without any one female being chased constantly. Buy…
One bristlenose pleco suits most tanks, and one male per tank is the firm rule, because adult males defend caves and can injure each other in scuffles over the best hollow. A male and female together are peaceful enough but will usually breed, filling cave after cave with fry you need a plan for, while two females are…
The safe answer for most homes is one betta per tank, because males are bred to fight rivals and will injure or kill another male, and many females are nearly as territorial. So-called female sororities can work for a few experienced keepers in large, densely planted tanks, but they fail often enough that a beginner…
Keep angelfish as a single fish, a confirmed mated pair, or a group of five or six juveniles raised together in a large, tall tank, and avoid the in-between numbers that invite a turf war. Two unpaired adults in a modest tank often become one bully and one victim, while a bigger juvenile group spreads the squabbling…
Zebra danios typically live for three to five years in a home aquarium, with the longest-lived fish usually coming from stable tanks where water quality, food and temperature do not keep swinging. A tight-fitting lid, a school of at least six and a long swimming run matter more for reaching that span than any special…
Swordtails live 3 to 5 years in a home tank, with the top of that range belonging to fish in roomy, well-covered aquariums. They are bigger and more athletic than their livebearer cousins, and two facts shape their span: they jump brilliantly, so an unsealed tank top ends more swordtail lives than disease does, and…
A true siamese algae eater is a long-term fish: 5 to 10 years is the expected span, with a decade entirely achievable in a roomy tank. The uncertainty starts at the shop, because several lookalike species are sold under the same name, and the common impostors differ in size, temperament and lifespan. A genuine siamese…
Platies live 3 to 4 years in a home tank, occasionally stretching toward 5 for a robust fish in stable conditions. They are among the hardiest beginner fish going, and what usually trims their span is not delicate health but genetics and generosity: most shop platies come from high-volume breeding where hardiness is…
Pearl gouramis live 4 to 5 years in typical home care, and a settled, unstressed fish in a calm community tank can reach 8. They are hardy once established, and what governs their span most is temperament — their own and their tankmates'. A pearl harassed by fin-nippers or crowded by boisterous fish lives under…
Can't find your question? Ask it here. We answer reader questions in KinsLe Answers — and we'll email you when yours is published.
KinsLe is launching soon — and the waitlist hears the date first. Join for launch updates and first access when the app opens.
We email you about the launch. Unsubscribe anytime.