The Algae Specialist, Correctly Identified
The true siamese algae eater, Crossocheilus siamensis, comes from the rivers of mainland Southeast Asia and holds a distinction almost no other aquarium fish can claim: it eats black beard algae, the dark tufted growth that defeats most cleanup crews, along with hair algae and the flat green algae on leaves, wood and stone. Between grazing bouts it rests characteristically on a broad leaf, propped on its pectoral fins, watching the tank go by.
Identification matters before diet does, because the name is borrowed freely in shops. Flying foxes and the so-called false siamese look similar at sale size but lack the appetite that makes the species famous. The true fish carries its black stripe unbroken from nose through the tail fin itself, with no gold band above it — checking that stripe at the shop decides whether the algae-eating reputation comes home with the fish or stays behind in the display tank.
Grazing Is the Job; Food Is the Top-Up
Here is the balance every keeper of this species has to learn: algae is the job, and prepared food is only a top-up. A young siamese algae eater grazes almost constantly and does its finest work then. As the fish grows, generous feeding quietly retires it — an adult that receives a full rich meal every day has no reason to spend hours rasping beard algae, and keepers regularly report a once-tireless cleaner that now waits under the filter for pellets like any other pet.
Supplements, then, are real but deliberately light. An algae wafer shared between the tank's grazers, blanched zucchini or cucumber slices, and an occasional sinking pellet or few frozen bloodworms keep the fish in condition without spoiling its appetite for work. In a tank with little algae growth the supplements matter more and starvation becomes the risk instead — the balance is struck by watching the fish's belly and the tank's leaves together, not by a fixed rule.
Tank Manners and Watch-Outs
Siamese algae eaters are fast, active fish that do well singly or in a small group, and their energy level shapes their tank manners. An underfed adult may develop an unfortunate habit: attaching to the flanks of slow, flat-bodied tankmates such as discus or angelfish to rasp at their slime coat. Keeping the supplements regular — light, but never forgotten — is the usual prevention, and a fish that persists should be moved to a tank of faster companions.
It is also worth saying what this fish cannot do. It grazes the symptom, not the cause: beard algae driven by excess light and nutrients will outgrow any grazer, and the lasting fix is in the lighting and feeding of the whole tank. A siamese algae eater that stops grazing, loses its clean lateral line to a pinched, hollow look, or is found hiding rather than resting in the open deserves a water test and, if that passes, a veterinarian's look. For the day-to-day, the lean supplement is exactly the feeding most likely to be doubled by a helpful second person — Care Teams in KinsLe logs each wafer and vegetable drop as a completed duty, keeping one fish's modest top-up from silently becoming three.