Can a red wag platy and guppies live together in a 5-gallon tank?

Unfortunately, aggression between species of fish is not uncommon. I am not sure if this is a new finding, or if anything has changed in the dynamic in your school of fish (any new introductions or any deaths of fish), but this often can then change how the rest of the fish interact with one another. You can try to give the platy places to hide and escape from the guppy, or you can end up dividing the tank. If you do not want to add dividers, you can also separate the guppy into another tank as well. I hope that gives you a place to start, and good luck!

I assume it is a male Beta? They typically are very aggressive and will kill other Fish. You could try to put a divider in the tank to keep them separate. I have seen those at most pet stores. Best of luck and thank you for using Pet Coach.

In general these fish can all be housed together safely. The one thing to keep in mind is the amount of space needed per fish to maintain a safe and healthy environment. Each 1in of fish needs 1 gallon of water. So in a 20 gallon tan you can have 20 inches of fish. The Pleco is the only one I have concerns with as some varieties can grow quite large. Check with your local pet shop as to what needs best suit this type of fish or what type of fish suit your tank best.

Yes, skunk cories reach 2 inches at adulthood. The general rule for tanks is one inch of fish per gallon of water. The cories will hang around the bottom while the guppies will cruise higher. Be sure to provide plenty of cover for the cories in case the guppies get nippy.

Both species are excellent "beginner" fish and quite easy to care for. Your 20 gallon tank is a good size for about 6 to 8 fish of this species. 10 would be close to overcrowding the tank. Once your tank is properly cycled, you can add your fish. They are omnivorous and will readily eat flake, pellets, freeze dried and live foods. Chemistry should be monitored regularly and kept as follows: ammonia 0ppm, nitrites 0ppm, nitrates 20ppm or less, pH about 7, water temperature between 76 F and 78 F. Provide moderate cover (hiding places). These fish are live bearers, so if you have male and female then expect fry (baby fish) at some point. If not separated, fry will likely be eaten by adults.

If the Betta is not acting aggresively, there is no need to remove him. Guppies, especially males, will fight with one another but it usually isn't serious. Providing plenty of cover for them to hide may be all you need. If the fighting persists, remove the aggressive guppy to his own tank.

The Tang, Clownfish, and Chromis are marine fish requiring a saltwater aquarium while guppies are freshwater fish. These fish are not compatible as they require two completely different setups to accommodate their different environmental needs. If you are going to set up a marine aquarium - a 20 gallon aquarium is too small for the fish you have listed. A small Percula Clownfish maybe suitable in a 20 gallon aquarium temporarily, but be prepared to upgrade to a larger aquarium as it grows larger. In general, 50+ gallon aquariums are recommended to properly house marine fish as they tend to grow large and require plenty of room to swim. If you are planning to set up a freshwater aquarium, a 20 gallon setup is adequate to house guppies.