Toothless, clawless and ultimately weaponless, African dwarf frogs don't pose much of a threat to most fish. Although the nearly blind amphibians might seem like they're picking fights with your other aquarium inhabitants, it's usually a case of mistaken identity. Still, their penchant for accidental nipping can cause trouble with long-finned fish. If your dwarf frog does seem aggressive, it's possible you have an African clawed frog.
African dwarf frogs don't have an ounce of aggression in their tiny bodies. Even two males can live together peacefully. Your frogs might seem aggressive toward each other, but that's typically either because they're crawling over one another or they're attempting to mate. When mating, they sometimes look as if they're hugging one another. They occasionally swim together or tumble through the water that way too. It's easy to mistake their mating positions for aggression.
African dwarf frogs have very poor eyesight. Most things are somewhat of a blur to them, and they often mistake something passing by their eyes for food. When a fish, snail or other frog flashes by your African dwarf frog, he might try to chomp down on them. This isn't a case of aggression. Your frog will probably only bite once or twice before he realizes he's not eating food. The dangers come when the target in question fits completely inside your frog's mouth, such as a fry. In that case, it's possible your frog could eat the fish accidentally.
In most cases, your African dwarf frog's occasional nipping won't harm your fish. But your frog's little mouth can tear the fins of long-finned fish, such as bettas. Fin injuries invite bacteria and fungus to invade, causing fin rot and other infections. If you notice your frog ripping away at your fish's fins, it's best to move either the frog or fish to another tank. Some fish -- bettas are notorious for this -- bite their own fins when bored or swimming in poor water conditions, so it's best if you catch your African dwarf frog in the act before moving one or the other.
Although African dwarf frogs don't mind the presence of other fish, that doesn't mean they can be housed with any and all fish. Do not keep your frog with highly aggressive swimmers, such as angelfish, or any fish that can fit the frog in its mouth. Although African dwarf frogs are extremely quick, their poor eyesight puts them at a disadvantage for sensing an oncoming attack from another fish. Plus, some aggressive fish won't tolerate being nipped at.
African Clawed Frogs
African clawed frogs, often mistaken for African dwarf frogs at a young age, are aggressive. Pet stores sometimes mislabel the two. If you're unsure whether you're looking at an African dwarf frog or an African clawed frog, look at the frog's feet. African dwarf frogs have webbing on their front and back feet. African clawed frogs have webbing on their back feet only. There's also a large size disparity when the frogs reach maturity. African clawed frogs grow to about 4 to 5 inches in length, while African dwarf frogs max at around 1 1/2 inches.