do u ignore my post or what gotta have aggressive fish with them they will nip that flagtail to death
+1 on this. Also, their water requirements are totally opposite. Flagtails are from SA (some of the world's softest water) and do best in soft acidic water. Tropheus are from the hardest most alkaline lake in the world (that fish live in). So, again, these fish would not be a good mix.
I never understand why people want to keep tropheus and the most asked question is "What can I mix them with?". Tropheus come in all the colors of the rainbow, they are lively, they use the entire water column, fairly easy to breed, and yet every noob wants to know what else they can put in the tank with them.
Species only is like a rule of thumb. Pick a variant you like and get as many as you can afford. Don't get 3 of one color and 6 of another and 5 of one more and expect success. Just pick one variant and buy as many as you can afford (12 minimum).
My honest to god advice is to save yourself some money and put the tropheus lust on hold for now. Wait until you are truly ready to get a large tank and dedicate it only to tropheus. To do it right is going to cost you about $2500. If you don't have the space or you can't give up that special fish that's in the tank where you want to put your tropheus, or you want to mix and match continents and lakes and species, then you aren't ready.
Believe me man, I do everything I am supposed to for my trophs and I still get deaths, and have to spend days changing water and dosing them with Metro/epsom salt battling bloat. And I don't make any mistakes like mixing them with other fish, and feeding them crazy stuff, or slacking on the water changes, or being cheap on the filters, etc, etc. The point is that even doing everything right they aren't easy to keep, so if you start out doing everything wrong you won't have any luck, you'll be angry you blew a ton of money on a bunch of fish, and now you have one mean fish in a huge tank (if any make it), plus they killed your prize flag tail....
If you do decide to get some check out this website: trophs.com
You'll find a lot of good information there. I would actually get a membership (it's free) and read as much as you can before you even sell the flagtail in preparation of buying tropheus. Tons of good stuff there, and if you actually do your homework and research the fish, when you ask the members questions there are a ton of really knowledgeable people who can help you with the bumps in the road you'll hit along the way.
Good luck
