What I mean is do they do OK by themselves in a tank or is it better to have 2 or more ???? The reason I'm asking is because today I woke up to find 1 of my 2 silver-tip Plecos dead. I'm really not sure what happened as all my water perimeters tested OK. I do know that 1 of the Plecos always took off whenever the other one got too close. I never saw any aggressiveness but there might have been some going on. Anyway - I was just wondering if I should add another pleco to my tank ( 30 gallon lightly planted Community tank ) or if the sole silver-tip Pleco will be OK on its own.