Hmmm...ok good food clean water and so on...get the idea...

another thing to consider is the breed. Sometimes in the farm(if urs is a common common pleco. There are a few variants available from liposarcus to Glyptopericthys ???) where they mass produce this fishes, they do not care about quality, so they just dump them together and hope something happens. So weak genes are passed down from one generation to another so tats why u encounter...poor quality individuals. There is a stock claimed to be anisitsi in Xian Leng Shah Alam going for 30bux. U can try it out and see since its imported...I'm not certain on the import part.

My plecos occasionally show bright nice colors...especially feeding time...even when water is dirty...will be splitting the population up as my 4ft can't handle the load