Can you put a betta fish in the same tank as Goldfish?

It's generally not recommended to put a betta fish and goldfish in the same tank. Here's why:

* Temperature preferences: Bettas prefer warmer water (78-82°F) while goldfish prefer cooler water (68-72°F). Maintaining a comfortable temperature for both species is difficult.

* Water conditions: Bettas are more sensitive to water quality than goldfish. Goldfish produce more waste, making it harder to keep the water clean enough for a betta.

* Aggression: Goldfish can be aggressive towards bettas, especially if they feel threatened or if the tank is too small.

* Fin-nipping: Goldfish have a tendency to nibble on other fish's fins, which can be harmful to the delicate fins of a betta.

Exceptions:

* Large tank: With a very large tank (at least 100 gallons) and carefully controlled water parameters, it might be possible to house a betta and goldfish together.

* Peaceful goldfish varieties: Certain goldfish varieties like fancy goldfish are less active and less aggressive. However, it's still risky as these goldfish can still be fin-nippers.

Bottom line: It's usually safer and more stress-free for both fish to be kept in separate tanks with appropriate water conditions.