+1 on this. Not only that but they grow incredibly slowly. I believe it takes something like 3 years from seed to flower in many of the plants.
I agree with this general idea. If you were to try to keep carnivorous plants with fish you would want to use a very light bio-load.
Many carnivorous plants also generally prefer to be outdoors with bright and very airy conditions and they suffer if you keep them for very long indoors.
Carnivorous plants also tend to have limited foliage--they don't need much leaf area for photosynthesis--so it would also be hard to get them to fill in and cover up the riparium planters.