[FONT=Geneva, Arial, Sans-serif]When I put tanks that are six feet or longer together and I'm thinking of how to mix different genus of Tanganyika cichlids, this is my thought process... 1) Rock dwelling tank / shell dweller tank: This means the tank is going to be filled with rocks except for one small area for the shell dwellers. Example: 6 Neolamprolgus buescheri 6 Altolamprologus calvus or Altolamprologus compressiceps 6 Shell dwellers: Lepidiolamprologus boulengeri, Lepidiolamprologus hecqui, or Lepidiolamprologus meeli 6 Julidochromis or 6 Neolamprologus leluepi Then you could add a large group of Cyprichromis. Twelve would be a good number to start with. With the above tank you would need to remove any extras from each group after a breeding pair forms. 2) The herbivores: This tank should be about half rocks. Example: 20 Tropheus 10 Petrochromis 6 Gobies: Eretmodus cyanostictus, Spathodus erythrodon, Spathodus marlieri, or Tanganicodus irsacae You can pick any variety of Tropheus you like but please stick with 1 variant as they tend to look better and get along better if there is only one type. With the Petrochromis, try and stick with the smaller less aggressive types. Two examples of these are Petrochromis fasciolatus and Petrochromis trewevasae. The gobies should eventually form a pair. Remove any extra gobies once the pair has formed. 3) Sand sifter tank: In a sand sifter tank you will need very few tanks. I would fill the tank 1/4th up with rocks. Example: 10 Sand sifters of your choice 12 Paracyprichromis 12 Cyprichromis If I was to set this tank up I would stick with the non-jumbo varieties of Cyprichromis. Sand sifters tend to stress out easily so if you stick with the less aggressive types you are more apt to have success. 4) Feather fin tank: With this tank I would only put a scattering of rocks, maybe 4 or 5 round rocks. Make sure the rocks are not sharp. Get 10 or so of your favorite feather fins. Paracyprichromis 12+ Even though Benthochromis tricoti are sometimes grouped into the feather fin category they are not true feather fins. If you want to try a tank full of tricoti I would suggest keeping them and only them in the tank. 5) The predators: These fish will appreciate a certain amount of rocks. In a six foot tank I would suggest making the tank at least 1/4th rocks. 8 Frontosa [/FONT] That's my basic guide lines, of course the rock dwelling tank can be changed up quite a bit, but this is how my thought process goes. Some Synodontis and other lake tang cats can be added to the tank depending on what you decide. P. typus is a good cat for the sifter / feather fin tanks. Synodontis petricoli make good additions to all of the above tanks. Most of these guide lines can be changed up quite a bit but hopefully this will help you make the perfect mix for your six foot or longer tank.