Hello Vic Alot depends on what you're looking to do. If your intentions are for breeding purposes, well the smaller tank could house 2 or three species if the decor is set up correctly.... making the tank set up like into 2 or 3 mini breeding areas would help seperate the species. I could see a nice Nijsenni, Cacatuoides and Viejita set up in a well planted and terraced 66 gallon tank. Now the larger 6 foot 108 gallon tank, i would say you could possibly do maybe 4 species. Now of course i really wouldnt recommend this at all. I would take the smaller 4 ft tank, plant the heck out of it, with some nice drift wood and rock work and put on of the larger species in there and let them colony spawn. Bitaeniata, Maulbruter, Elizabethae would come to mind as a single species colony tank. Believe me when i say this sort of tank set up looks awesome, as ive spawned all three species in 55 gallon tanks where i had 2 males and maybe like 5 - 7 females with appropriate amount of flower pots or caves set up in the tank for each male and female to hide in. Once a pair sets up an area and fry start appearing in the tank, the other females end up spawning and fry swim through out the tank intermingling with other fry to the point no one really knows whos fry is who. I just remove the largest fry sometimes as they start becoming sexable to another rearing tank for grow out and potential spawning... The larger 108 gallon tank, well plant it heavily, set it up with lots of caves and driftwood and see what works...... just put in fish from diferent complexes so that no potential hybridization could occur. Also keeps potential fighting down as males wont court females not related to themselves....I could see a very nice Cacatuoides, Panduro and Aggie tank set up. Be creative and start slow and go easy and see what works..... If you're not interested in breeding purposes, you could put tons of different males in those tanks and would have lots of great color!! You might even want to try mixing in some bolivian rams and Nanacaras.... John Wubbolt Tupper Lake, NY ----------------------------------------------------------------------- -- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. apisto-digest@listbox.com also available. Web archives at http://lists.thekrib.com/apisto Trading at http://blox.dropship.org/mailman/listinfo/apisto_trader