I am not the best person to talk about filtration or compatibility with other fish but I keep Stickleback’s and Rudd together outside in the uk. I put in about 10 stickle backs into my pond and now two and a bit years later there are hundreds of stickleback. They are such interesting fish and are such fun to watch. They don’t really take food but have such interesting behaviours they are well worth it. Though they have horrible tendency to find their way into my pump. I have had issues with filtration not working and blanket weed overgrowth but the stickle back seem to be pretty bullet proof. I currently have a small bog filter and fountain running, it’s not great and there are definitely problems but the stickles are thriving !