Bas Pels wrote:I agree with Mats that this fish is not to be recommended for a Malawi tank, but due to its shyness and the eventual larger sensitivity to hars/ alkaline water
In my experience, most pleco's seem to not be too bothered with alkalinity/hardness - aside from some particularly sensitive blackwater species, which aren't exactly the common varieties that we talk about here...
I think you're right that the G. punctatus is a little bit slower growing, and it's ultimate size appears to be smaller too - at least if you believe fishbase
. But 28.5 cm SL is still a good size too big for a US 55g tank, as the tank would be about 13" wide, and the fish a shade over 11" - a bit big in my opinion at least. Yes, I know, fish in captivity don't always reach the maximum wild size, and so on, but I still think a fish that potentially grows to ALMOST the same size as the width of the tank is too large for the tank, even if they don't reach their full potential growth...
Generally, it's said that Glyptoperichthys species loose their "taste" for algae when they grow up. So that may be why you feel that the gibbiceps aren't quite as good algae eaters... On the other hand, you may also be right - I don't keep either species, but I've seen plenty of people on Planet Catfish that are trying to "do something about" a 8, 10 or 14 inches long "common pleco" that they have in a tank not so suitable for that size fish.