I would not think the behaivour of a Ery Ery would be much different Ery. Sp. Peru. I think they would have a very similar group dynamics. I would be farily confident that a group could be kept together if certain criteria were met. 1. Tank size & shape 150+ 2. proper aquascaping- many tubes, caves, heavily/densly planted lower to mid sector of the tanks, floating plants also to dim some of the light. 3. Raisng them together from the start... 4.mild current to make sure they feel comfortable in all areas of the tank. ..... I do not think that when most people are trying to keep these together they supply the proper set up because they want to see the fish more( understandable)... however I strongly believe that keeping abudance of tubes and caves with heavy planting like Java Moss is the key. allowing for many breaks in their lines of sight from each other is very important. Mine sometimes will stay hidden all day/night.