Is it bad to put tropical fish in with river fish?

It's generally not a good idea to put tropical fish in with river fish. Here's why:

* Water Parameters: Tropical fish and river fish have very different water parameter requirements. Tropical fish need warm, stable water with a specific pH, while river fish are adapted to cooler, fluctuating temperatures and different pH levels. Mixing them can cause stress and health issues for both types of fish.

* Diet: Tropical fish usually require a specialized diet of flakes, pellets, and live foods, while river fish often prefer insects, worms, and other natural foods. Feeding them the same diet could lead to nutritional deficiencies.

* Behavior: Tropical fish and river fish may have different temperaments and social behaviors. Some river fish can be aggressive towards smaller tropical fish, and tropical fish might not be able to handle the cooler temperatures and currents of a river environment.

* Disease: Introducing fish from different environments can increase the risk of spreading diseases. River fish may carry parasites or bacteria that tropical fish are not immune to, and vice versa.

Exceptions:

While it's generally not recommended, there are a few exceptions:

* Some River Fish can Tolerate Warm Water: There are some river fish species that can adapt to warmer temperatures.

* Species-Specific Compatibility: Researching specific fish species can sometimes reveal compatibility. For instance, some smaller river fish may co-exist peacefully with certain peaceful tropical fish.

It's always best to research the specific requirements of each fish species before introducing them to the same tank.

If you're unsure, it's best to keep tropical fish and river fish in separate tanks to ensure their health and wellbeing.