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The husbandry concepts that decide whether a tank works — group requirements, quarantine, feeding, stocking and responsible practice.
Feeding (1)
Behaviour (7)
- Group size and social requirementsMany aquarium fish are obligately social, and a group below their threshold produces sustained stress behaviour rather than merely a quieter tank.
- Tankmate compatibilityCompatibility depends on water requirements overlapping, on adult size difference, on behaviour, and on the tank having the dimensions the combination needs. It is rarely a simple yes or no.
- Schooling and shoalingShoaling is staying near others of your kind; schooling is moving with them as a coordinated unit. Most aquarium 'schooling' fish shoal, and the number that matters is the one at which the behaviour appears rather than the one at which the fish survive.
- Predator and prey sizeA fish eats what fits in its mouth. Temperament decides how often it tries; gape decides whether it can succeed, and gape is a fact about anatomy that no amount of good nature changes.
- Territorial behaviourTerritory is a defended area with a shape, and the shape is what decides whether a tank works. Two fish that both defend the floor conflict; one that defends the floor and one that defends the surface frequently do not.
- How to read a compatibility verdictMost compatibility verdicts anywhere, including here, are arithmetic on stored traits rather than reports of what actually happened. That arithmetic is sound and it is not the same claim, and a system that presents the two identically is overstating the first — precisely on the pairings nobody has tried.
- Why body shape decides what gets eatenThe hobby's rule is that a fish will attempt anything under about 40% of its own length. That is a statement about one shape of predator and one shape of prey, and it is wrong in both directions for everything else: it over-warns about deep-bodied fish and badly under-warns about slender ones.
Maintenance (2)
- Routine maintenanceA weekly partial water change with a substrate vacuum, a monthly filter rinse in tank water, and regular observation. Consistency matters more than intensity.
- What a specific gravity reading actually meansA hydrometer reading is a comparison, not a measurement of salt: your water against pure water at whatever temperature the instrument was scaled for. Two temperatures are therefore built into every such figure, and one quoted without them cannot be turned back into a salinity by anybody.
Acclimation (1)
Health (1)
Setup (1)
Welfare (5)
- Stocking an aquariumStocking is decided by adult size, footprint, social requirements, territory and filtration — not by a number of fish per unit of volume.
- Biosecurity and responsible disposalAquarium animals, plants and water must never enter the wild. Released aquarium life is one of the main pathways by which invasive species establish in fresh water.
- Aquarium welfareWelfare means providing the conditions in which an animal can express normal behaviour, not the minimum in which it can survive.
- Wild conditions and aquarium recommendationsA measurement of the water a species was found in and a recommendation for the water it should be kept in are different claims. They look identical once written down as a pair of numbers, and AquariumHQ stores them separately for that reason.
- Rehoming an animal you can no longer keepIn order: a specialist keeper, a local aquarium society, a shop that will take it, a public aquarium, and — where nothing else is available and the animal cannot be kept adequately — humane euthanasia by a competent person. Release is not on the list, in any jurisdiction, for any species.
Identification (2)
- Scientific and trade namesA trade name tells you what a shop calls an animal. A scientific name tells you which animal it is. They agree often enough that the disagreements are dangerous.
- Why fish size figures disagreeBecause they are usually measuring different things. Standard length excludes the tail fin and total length includes it; a maximum is the largest specimen anybody recorded and a typical size is what a well-kept adult reaches; and a taxonomic checklist records the biggest fish its compiler examined, which is not the same as the biggest the species gets.
Distribution (4)
- Native, introduced and invasiveNative, introduced, established, invasive and illegal are five separate claims. Each is a stronger statement than the last, none of them implies the next, and the hobby collapses all five into one word.
- The kinds of water aquarium fish come fromAquarium fish come from about twenty recognisably different kinds of fresh water, and the differences between them are larger than the differences between most species. Knowing which kind a fish comes from tells you more about how to keep it than its common name does.
- How aquarium species get into the wildBy more routes than the hobby's own discussion suggests. Deliberate release by a keeper is documented and is not the dominant one — ornamental fish farm escape, aquaculture, angler bait buckets, deliberate government stocking, classroom release and ballast water all appear at least as often in the records.
- What a legal restriction on a species actually meansFour different things get called 'banned': possession, sale, import and release are regulated separately and frequently differ, and a species can be prohibited to import and legal to keep, or invasive and entirely unrestricted, or restricted somewhere it could never survive.