Angelfish

The missing measurement is height

The familiar 15 cm figure is standard length, excluding the tail. Adult angelfish can also stand 20 cm or more high across their fins, according to Seriously Fish's species profile. That vertical span changes the aquarium choice. A long, shallow tank is not equivalent to a tall one, and a narrow tower does not supply the horizontal territory missing from its base.

For one established adult pair with no additional companions, Tankwise uses at least 100 x 40 x 50 cm (length x width x height), about 200 L nominal, as a conditional long-term purchasing plan. The dimensions come from the SF reference; assigning them to this pair-only plan is our editorial judgement, not a source-certified minimum for a pair. Neither SF nor the accessible Fishkeeper account establishes a permanent adult-group capacity for this tank.

Before buying, check the furnished space, not just the litre label. Glass, the air gap, substrate and decor reduce the nominal volume. Both adults must be able to swim and turn with their fins extended, without squeezing between furnishings or having their vertical clearance cut off by branches. Provide sight breaks and separate retreats without blocking those routes, and have suitable separate housing ready. If the proposed layout or backup cannot meet these conditions, do not buy the pair for this setup; choose different accommodation or postpone the purchase. More height alone cannot repair a cramped footprint.

Arrange tall plants and wood to interrupt sight lines while leaving broad passages for the fins. Keep filtration established and flow gentle enough for the fish to hold position comfortably. Taller water does not replace oxygenation or regular waste removal.

A juvenile group can become a territorial problem

Both Fishkeeper and SF describe group keeping, but neither supplies a permanent adult-group count for the reference aquarium. SF's suggestion to begin with six juveniles is a breeding strategy for obtaining a pair, not permission to keep six adults indefinitely in it. This page does not provide an adult-group purchasing count or tank-size plan. If a group is your goal, arrange an individual assessment of a larger aquarium, adult territories and relocation options with an experienced angelfish keeper or specialist retailer before buying; do not use the pair-only plan as a group allowance.

The pair-only plan means two mature fish already living together as an established pair. Ask the supplier about their observed pairing and cohabitation history, including whether either fish is chased away from food or shelter. Two unsexed shop juveniles do not meet that condition, and buying an apparent male and female does not establish compatibility; SF notes that sex is difficult to determine outside spawning. Even an established pair may become unsafe together. Have a separate, established aquarium suitable for an adult ready before bringing them home, rather than relying on finding a new owner after aggression starts.

Watch the fish at feeding time and between meals. A fish confined to a corner, repeatedly driven behind the filter or denied access to food is not merely settling into a harmless hierarchy. End the unsafe combination before injury; adding more fish or rearranging a few ornaments is not a dependable solution.

Choose neighbours for the adults you will have

No tankmates are included in the pair-only space plan above. Adding any companion requires a separate space and territory assessment, not merely matching water parameters. Adult angels can eat small fish such as neon tetras. The species profile explicitly flags this predation risk; a peaceful juvenile stage is not evidence that the combination will remain safe. Avoid fin-nippers, and assess the adult size, territorial behaviour and long-term water needs of every proposed neighbour. A bottom-dweller still enters the territory of a spawning pair.

For domestic stock, our routine planning band is 24-28 C and GH 2-15 dGH, within SF's broader 24-30 C and 0-15 dGH reference ranges; pH 6.0-7.4 follows that reference. These are planning values, not instructions to push an established aquarium to an endpoint. Ask the supplier about the stock's water, and do not choose tankmates whose suitable conditions only meet at an uncomfortable extreme.

Check who gets the food, not just who approaches

Use appropriately sized complete pellets or flakes, with small frozen invertebrates for variety, as described in the feeding reference. Watch each angel swallow food. A dominant fish may be conspicuous at the front while another gets very little; separate feeding positions can help you see whether everyone is actually eating.

Remove leftovers and review ammonia, nitrite and waste accumulation when fish grow or the population changes. Match partial water changes to those observations rather than assuming a fixed weekly percentage covers an expanding group. If food access stays unequal, change the social arrangement instead of increasing the ration for the whole tank.