Welcome to AA. First I would split up the turtle and the fish. As aquatic turtles main diet consists of fish. Turtles need at least half a tank of water and a dry area to bask in. They need a heat lamp and a uv
lamp and a strong filter and at least a 40g breeder tank to house it.
As for the fish. Krib females get a red belly and the males don't. You night be able to get away with a fire mouth in there with them but keep in mind that they get good size and can get aggressive and you could lose your kribs. I would go with some more kribs, a school of barbs, some loaches, or something along those lines.
Hope this helps