* Different water parameters: Goldfish prefer slightly cooler water (65-72°F) and are more tolerant of higher pH levels. Fire belly frogs prefer warmer water (72-80°F) and a more acidic pH. Maintaining optimal conditions for both species would be challenging.
* Dietary needs: Goldfish are omnivores and require a diet of flakes, pellets, and occasional live food. Fire belly frogs are carnivores and need a diet of insects, worms, and other small invertebrates. Feeding both species appropriately in the same tank can be difficult and might lead to one species going hungry.
* Behavioral differences: Goldfish are active swimmers and can be disruptive to frogs, who prefer a calm and quiet environment. Goldfish may also accidentally injure frogs while scavenging for food.
* Disease risks: While it's not a certainty, there is always a risk of introducing diseases to one species from the other.
Instead of keeping them together, it's best to provide separate tanks for goldfish and fire belly frogs. This will allow you to maintain optimal conditions for each species and prevent any potential problems.