What other types of tropical fish can be successfully kept with discus? Cardinal tetras are probably the best companion fish for your discus aquarium. First of all, a group of cardinal tetras are simply beautiful tropical fish. They are fun to watch. Cardinal tetras are also very suitable with the warm, acidic water that discus like. Finally, cardinal tetras are dither fish. Dither fish can have a strong calming effect on more timid, larger fish like discus. The small dither fish swim back and forth in the aquarium, out in the open. The discus notice that these small fish seem secure in their environment. That gives them a signal that everything is safe in their enclosed environment and allows them to come out into the open without any fear. If you ever have shy, skittish discus that always seem to hide, you might want to add a school of cardinal tetras to your aquarium.
Corydoras catfish are another good fish to add to a discus tank. Adding a few corydoras catfish to the tank will help with clean up maintenance. They will scamper around the aquarium looking for any particles of food that have not been eaten. This will help keep the aquarium water cleaner and your discus will be much happier for it. If you add coryadoras to you discus aquarium, try to keep the water temperature around 82 - 83 degrees. Corys don't like the higher temperatures. Sterbai
Ancistrus are also suitable tank mates for your discus. These fish will help keep your tank clean by eating the unwanted algae that forms in your aquarium. Make sure you supplement the ancistrus's diet with some quality algae wafers on a regular basis and add a small piece of driftwood in your tank to help them digest their food.
Other suitable tank mates for discus include: clown loaches(make sure they have a place to hide in the aquarium), German blue rams, rummy nose tetras, glowlight tetras and rosy tetras.
What tropical fish should you avoid putting in with discus?
You should avoid keeping large tropical fish that can intimidate discus or will compete aggressively with them for their food. Fish like oscars, piranhas, severums and flowerhorns fall into this category.
Angelfish is another fish that should not be kept with discus. They are too aggressive, especially when they reach sexual maturity and will try to take over the entire tank forcing the discus to hide. Angelfish are also very quick eaters and might cause your discus to miss out on food.
Avoid fish that don't like warm, acidic water that discus prefer. So don't put any African cichlids in with discus. Also don't put neon tetras in with discus since they prefer much cooler water.
Finally, don't put in fast swimming, fin nipping fish. Fish like tiger barbs, danios or tinfoil barbs will damage your discus by nipping their fins and will make them very skittish.
Tank mates for discus breeding pairs?
Discus breeding pairs should be kept alone. They might spawn in a community tank with other fish, but the fry will almost never survive. If the other fish in the aquarium don't eat the discus eggs or wigglers, the discus parents usually will, to "protect" them. Always keep discus breeding pairs alone in their own aquarium.
Remember that discus are shoaling fish and do best in groups of 5 or more. They feel much more secure and have less stress in large groups.
Finally, never add young, small size discus into an aquarium with significantly larger discus. The larger discus will bully the younger fish causing them stress. The larger discus will also aggressively eat most of the food causing the smaller discus to go hungry, get weaker or sick. Over time, the bullying of the smaller discus might cause them to become stunted. Grow smaller discus in a separate tank and then add them with your larger discus when they are close to the same size to avoid any problems.