A siamese algae eater spends its working life in contact with surfaces, grazing algae from leaves, glass, wood, and the floor itself. That habit decides the substrate: smooth sand or fine, rounded gravel, with no sharp or jagged grains against a mouth and belly that are pressed to the ground for much of the day.
Why Smoothness Matters More for This Species
These fish rasp at algae film with a down-turned mouth and rest on their pectoral fins between bouts of grazing. On coarse, angular gravel, that constant contact can leave the underside and mouth area looking sore or worn, and food particles fall into gaps the fish cannot reach, where they rot instead of being eaten. Sand and rounded fine gravel keep both the grazing and the resting comfortable, and they let the fish pick up small food items cleanly.
The floor also has a second job. Siamese algae eaters graze heavily on broad plant leaves, and a planted tank needs a substrate that roots well. Fine grains anchor stems while still allowing the fish to work along the base of each plant, which is exactly where algae film tends to build up unnoticed.
Setting the Depth and Layout
Lay the substrate deep enough for rooted plants, keeping open swimming and grazing stretches at the front rather than filling every inch with hardscape. These are strong, active swimmers that also like to perch, so flat stones or wood sitting on the floor give them resting spots without changing the grain of the floor itself. Rinse the material well before it goes in, and add it before planting so roots go into a settled bed.
Leave a clear lane along the front glass. Algae eaters patrol predictable routes, and an unobstructed front section makes it easy to watch whether each fish is grazing actively, resting normally, and holding good body condition. It also makes vacuuming that busy area simple without dismantling the planting behind it.
Keeping a Grazed Floor Clean
Because these fish stir the bottom as they feed, debris gathers in the quiet corners behind wood and dense stems. Vacuum open sand or gravel weekly with the water change, hovering over sand and dipping lightly into fine gravel, and clear those hidden corners before trapped waste starts to affect water quality. Uneaten wafers or vegetable pieces should be lifted out once the fish lose interest, rather than left to soften into the floor.
Take care when replanting or moving hardscape not to bury a resting fish's favourite patch under a mound of displaced substrate. These fish return to familiar perches, and a stable layout lowers the scuffling that can happen when several algae eaters renegotiate resting spots in a changed tank.
When the Floor May Be the Problem
An algae eater that stops grazing, sits listlessly, or shows a reddened mouth or underside should prompt a water test and a close look at the substrate. Sharp new gravel, a floor fouled by missed corners, or a tank where this fish is being outcompeted at feeding time can all sit behind the change. Healthy fish are almost always moving, tasting surfaces as they go, so a sudden stillness stands out.
Writing down the grain type matters in a community tank, because replacement substrate bought in a hurry is often the sharp-edged kind sold for decoration. KinsLe Family Sharing puts the smooth-substrate requirement in the tank's shared care details, so whoever buys supplies or cleans the floor keeps the grazing surface safe for these fish.