First, buy the right fish
More first tanks go wrong at the shop counter than at home, because several different fish are sold under the siamese algae eater's name. The true species has a black stripe that runs in one unbroken line from its nose through to the fork of its tail, plain transparent fins, and a habit of resting propped up on its pelvic fins like a tripod. The common impostors matter: the Chinese algae eater grows aggressive, stops eating algae and starts rasping the slime coat off other fish, and the false siamese has a stripe that stops before the tail. Learn the tripod rest and the through-tail stripe before you shop, and buy from staff who know the difference.
Length, flow and a fitted lid
A true siamese algae eater is an active, riverine fish that grows to around 6 inches and swims constantly, so a first tank needs at least 30 gallons arranged long rather than tall - swimming length is the dimension this fish uses. In the wild it grazes rocks in moving water, and it does best in clean, well-filtered, oxygen-rich conditions around 75 to 79 degrees, with enough gentle current to feel at home. Decorate with smooth stones and driftwood to graze, plants it mostly leaves alone, and - non-negotiably - a tight-fitting lid, because these fish jump with intent and find gaps at corners and pipework that other species never test.
The algae years, and the feeding after them
Young siamese algae eaters are famous for one skill: they are among the very few fish that reliably eat black beard algae, the stubborn tufted algae most crews ignore. But they are not algae machines, and an adult that is never fed becomes a lazy grazer that waits for fish food instead. Offer algae wafers, blanched vegetables and ordinary sinking foods as a regular part of the diet from the start, and let algae be the supplement rather than the meal. A well-fed siamese keeps grazing; a starved one gives up on the job you bought it for and may start investigating slow tankmates instead.
One, or a proper group
Socially these fish sit in an awkward middle: a single siamese is usually peaceable in a community tank, and pairs or trios often squabble, while groups of five or more in a large tank spread the friction and behave more naturally. For a first 30 to 40 gallon setup, one is the sensible stocking. Tankmates should be peaceful community fish that enjoy similar conditions; avoid very slow, long-finned species if your individual proves pushy at feeding time, and do not combine a siamese with the aggressive lookalikes it is so often confused with. Given clean water and room, expect a lifespan of around ten years.
Watching a new fish settle
A settled siamese works the tank all day - grazing decor, resting in the tripod pose between bouts, and surfing the filter current. New fish may sulk for a day or two, but continued hiding, rapid breathing or loss of interest in grazing usually points at water quality first, since these are river fish with little patience for ammonia or low oxygen. Test before treating, increase surface movement if breathing looks laboured, and remember that a fish sold for a job still deserves the conditions of its own species, not just a dirty tank to clean.
Identification is the whole game with this species, and it is a local-knowledge game: KinsLe's Pet Services Directory connects you with trusted aquatics shops in your area whose staff can tell a true siamese from its impostors before one ever reaches your tank.