I have 3 plecos in my angel and tetras tank. It is a 40 gallon tank, standard size. The plecos are 2 rio de paras, and 1 three beacon pleco (vampire family). I think the rios are a pair, but that's not based on anything scientific, just observations of the intensity of their coloring. There are 2 pieces of wood and a rock in the middle of the tank. Lately, the paler rio de para has been behind the filter pipe during the day. When I throw down food, the paler one goes for it, but then the brighter rio de para comes off the wood and chases him away. So I'm thinking I have two problems. Number one, I need to see if I can feed the plecos in two separate areas of the tank, and number two, if I add more wood, and rearrange it the length of the cave, will each rio have enough territory. If that doesn't help, then I figure it's time for one rio to be sold off. If I sell off one rio, will the other two plecos continue to get along? I've never kept mixed species of plecos before, so I'm hoping that the three beacon and the rio will continue to not care very much about each other, even as they grow.

The three beacon is the largest of the plecos, he is about 4 1/2 inches and just a stockier fish in general. The rios are more slender, and are maybe 3/4 inch shorter than him.

There are no actual battles going on, all fins are in perfect condition, but I can see where this may be heading, so that's why I'm just putting these ideas out there. These fish have been together for at least a year now, if not longer.

The extend of my pleco knowledge is more then limited. I know that they keep the tank clean, that's about it. However, I too keep mixed plecos in my SA and CA tanks and have no aggression problems.

I think that's probably your best bet. If the dominant fish won't allow the other one to eat, it will starve to death eventually. I would be wary of saying you have a pair though. The brighter colours could just show dominance.