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 23 of 24
Watch the whole tank before the individual fish: choose goldfish that swim level and steadily, hold their fins open, breathe calmly, and compete eagerly at feeding, with clear eyes, smooth skin, and a body well filled behind the head rather than pinched or hollow. Reject any fish that rests on the bottom, clamps its…
Judge a line across generations, not by its prettiest male, because inbreeding shows up as a pattern that repeats in litter after litter. Warning signs include curved spines, adults that stay runty, males whose color looks washed out, fry that arrive deformed or fade early, and fish that seem listless at an age when…
Pick by species, not by the word snail on the tank label: nerite snails are the safest planted-tank choice because they graze algae and biofilm and cannot manage healthy leaves, and mystery snails generally take decaying matter and leftover food, nibbling only soft, already-dying growth. Avoid unidentified large…
Judge behaviour before colour. A healthy angelfish swims level and upright in open water, holds its fins extended, breathes steadily, watches you, and comes forward when food appears. One that is merely enduring hides low or in a corner with fins clamped, breathes fast, hangs at a tilt, or ignores food, even when its…
Choose species-only if you want breeding you can watch: berried females carry eggs undisturbed, shrimplets graze in the open, and no fish patrol the moss for them. Choose community if shrimp are supporting cast in a fish display, accepting that even small peaceful fish eat some shrimplets and the colony grows only…
Start from a test of your own tap water, because the shrimp that breed readily are the ones whose hardness range your water already sits inside. Cherry-type shrimp are the forgiving example: they tolerate typical tap water across a wide hardness range and raise young in the same conditions their parents live in.…
Keep males only. Male guppies are the smaller, vividly coloured ones with the flowing tails, and an all-male group cannot produce a single fry, so the population you buy is the population you keep. Females are larger and plainer, and they undo the plan twice over: a female can arrive already pregnant from a mixed shop…
Build the first group around one species kept properly: six or more tetras of the same kind, of similar size, will school, feed, and settle in a way that two each of three kinds never will. Choose a hardy species whose adults stay small enough for your tank and whose temperament is peaceful, such as ember, neon,…
Choose short, light finnage. Plakat bettas, which carry the short fins of the wild form, swim strongly, explore the whole tank, and rest by choice rather than exhaustion, and other short-finned types such as standard females share that freedom of movement. Avoid the heaviest show forms: very long-finned halfmoons,…
Judge the variety by the adult it becomes. Slim, single-tailed goldfish such as commons and comets are fast, powerful swimmers that can pass 12 inches (30 cm) in length, and they belong in a pond where they have room to cruise and turn. Round-bodied fancy varieties with double tails, such as fantails and orandas, swim…
A tank card that calls a cichlid peaceful is giving you a sales shorthand, not a temperament assessment. Research the exact species instead: its adult size, whether it defends a spawning pit or a cave, and how it treats its own kind compared with other tank mates, using species profiles, breeder notes and keeper…
A single clownfish or a bonded pair of the common ocellaris type does well in a saltwater tank of about 20 gallons, which gives stable water conditions and enough rockwork territory for the pair. Go larger — 30 gallons or more — for bigger species such as maroon clownfish, for a busier community, or simply to make…
For a small tank, choose from nerite snails, amano or cherry shrimp, or — in a tank of twenty gallons or more with established growth — a small group of otocinclus catfish. All stay tiny and work glass, leaves and decor gently. Avoid the common pleco, which can pass a foot in length, and the siamese algae eater and…
Choose peaceful species that use different levels of the tank and thrive in soft, planted water: a schooling group of small tetras or rasboras for the middle, a small group of corydoras for the floor, and a calm centrepiece such as a honey gourami up top. Add stock in stages to a mature, cycled tank, keep schools at…
Past the tank, heater and filter any aquarium needs, a marine setup adds marine salt mix for making seawater, purified RO/DI water, a protein skimmer, live rock, test kits for salinity, ammonia, nitrite, nitrate and pH, and a refractometer to check salinity accurately. Corals also need stronger, reef-suitable lighting…
A new saltwater tank typically takes four to six weeks to cycle, meaning grow enough beneficial bacteria to convert ammonia to nitrite and then to the far less harmful nitrate. Tanks started with quality live rock can be ready sooner, sometimes in two to three weeks, while dry rock and a bare start can take six to…
Match the colours to your fish and to their comfort, not only to the room. A dark background, in black or deep blue, makes pale and brightly coloured fish stand out, hides cables and algae marks, and removes the mirror-like reflections that can unsettle shy fish. Dark substrate deepens the colours of many tropical…
A single angelfish is fine, and for many home tanks it is the easier choice. Angelfish are cichlids with a territorial streak: a bonded pair can bully every other fish when spawning, and a group of adults often squabbles over rank and space. One fish kept alone does not pine for its own kind; it patrols its plants,…
Yes. Captive clownfish do not need an anemone to live well, and many home tanks are easier to keep stable without one. In the wild the partnership protects both animals, but a tank-bred clownfish has grown up without that protection and usually settles somewhere else instead, hovering over a soft coral, hugging a rock…
Ask how the fish were kept, what water they live in now, and whether the seller can show feeding and health notes before you pay. Check adult size, lifespan and tank needs against the space and time you truly have, and ask what happens if the fish outgrow your setup. In KinsLe, Transferrable Profiles let a pet's…
The best first fish is a hardy species that stays small, tolerates the small water swings every beginner makes, and is already eating well in the shop. A single betta in a heated, filtered 5- to 10-gallon tank suits a small setup; for a 20-gallon, white cloud mountain minnows, zebra danios, or a small group of…
A 20-gallon long tank is the sweet spot for most beginners, with a 29-gallon a close second if you have the space. More water changes more slowly: a slight overfeed or a missed day in a big tank nudges temperature and waste levels, while the same slip in a 5-gallon bowl can swing them hard overnight. Twenty gallons…
For a first freshwater aquarium you need the tank itself with a lid and a level stand, a filter matched to the tank size, a heater and thermometer for tropical fish, a light, rinsed substrate, water conditioner that removes chlorine, and a liquid test kit for ammonia, nitrite, and nitrate. Add a dedicated bucket and…
For a new freshwater aquarium, the forgiving choices are hardy livebearers such as platies and guppies, zebra danios, white cloud mountain minnows in unheated tanks, and corydoras catfish once the tank is settled. Hardy still means a fully cycled tank, stable temperature, and light stocking — no fish tolerates ammonia…
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