I recently purchased three of these fish and kept them in my cold water goldfish tank. The shop sold them as 'butterfly algae eaters from China'. Here in the UK they cost about US$9 each. I brought them hoping they would help to 'clean up' the tank/glass, but they are very shy and I rarely catch them eating. When they are active they glide mid-water from one side of the tank to another like a mini stealth fighter plane. They seem to prefer well aerated tanks with heavy water movement. They like to stick against the glass closest to the outflow of my power filter. There does seem to be some confusion as to what temperature these fish should be keep at, mine are at about at 19°C and doing fine. If these fish are from Hong Kong then it would explain the range of temperatures they can survive at.
Mine is active day and night. It spends 99% of its time clinging to the walls, and it is very efficient at removing algae. I feed it shrimp pellets, which get stuck in the plant leaves, where the fish can reach them without interference from other fish.
I have two of these, and they do like to be in the area where the bubbles are, and staying mostly on the sides of the tank. Sometimes they will come down to the tank bottom and feed on an algea chip. What I like about these is that they do not get real big.
I notice a lot of people think the hillstream loach is an algae eater or a pleco. The one I had rarely ate algae. It, like other loaches, fed off the food that fell to the tank bottom. I think the habitat is what is cause this confusion. Everything I've read about it says that they cling to algae covered rocks that lie in brisk current. But the books go on to say that they don't eat the algae as a dietary staple, but feed off the bottom on smaller animals.
My Hillstream loach is not shy, but pretty territorial. It lives on a big rock with which it blends quite well, and stays there even when I am moving it around! It also spends a good amount of time on the glass. I know other people said it doesn't eat the algae, but since I bought it, my tank is spotless, so I do believe it does. I have a small 75 liter community tank, and the water is about 27°C. I feed my fish flakes and I've seen this loach eat them, at the bottom. I recommend this cute and small fish to everyone.
I have one in my tank, it was sold to me as Beaufortia leveretti though, and I was told this was actually a catfish. Now I am wondering if these are two different species that look exactly alike or the same. Mine has adapted well to the tank anyway, it is not very shy, often it is feeding on tablets at the front of the tank tohether with my Kuhlli loaches and my approach is no reason for him to stop eating. I often see it during the day, sticking on the glass, especially after a waterchange. It is a very nice animal to have!