Bullfrog (Rana catesbeiana)
Reaching a length of 8 inches, the bullfrog is the largest frog in North America. It is native to the eastern half of the United States but has been introduced throughout the country and also in many other places, such as Japan and England. The bullfrog's large meaty legs are a delicacy in many places, and escapees from frog farms are largely responsible for the introduced populations.
Tadpoles of the bullfrog are also quite large, growing to a length of 4 inches. This renders it very easy to observe the transfer from tadpole to frog, and their overall hardiness makes these tadpoles ideal subjects for classroom study. Unlike most temperate frog species, bullfrog tadpoles take a relatively long time to transform. Especially in the northern parts of their range, the tadpole stage can last for up to two years (they hibernate during the winter).
Tadpoles may be housed with nonaggressive fish, but be aware that they are extremely slow feeders and will not be able to compete with fish for food such as fish flakes. If kept with fish, tadpoles should be fed greens or other items that the fish do not favor.
Bullfrog tadpoles can be kept in an aquarium at normal room temperatures. They do not favor fast currents, so filtration should be mild. They are ravenous eaters and should be fed daily. They will accept commercial fish food flakes, algae tablets, and various greens, such as kale, that have been soaked in hot water to render them more digestible. The front legs will develop first, followed by the rear. Once the fourth leg has appeared, the tadpoles generally stop feeding until the tail has nearly disappeared. At that time, they should be provided with an easy method of exiting from the water. Although they will crawl out onto cork bark floats in relatively deep water, it is safer to transfer them into a tank with a lower water level with easy access to floating plants, rocks, and other dry areas. Or they can be provided with a tilted aquarium, so that one-side is left dry (this area should be provided with some cover, as they are fairly shy animals).
The young frogs make ideal pets, but they do require live food in the form of insects, small fish, and earthworms. Be aware if one frog does outgrow the others, their prodigious appetites include a taste for frog meat as well! Adults are voracious predators and will take anything that fits within their capacious mouths, including rodents, young turtles, and birds. The frogs will be quite shy for some time and should be provided deep water in which to retreat. Many individuals become quite tame after a time, even to the extent of feeding from the hand. Adult bullfrogs will require a 20 gallon or, preferably, a 30 gallon aquarium to themselves. They can be fed earthworms, crickets, crayfish, and other insects as may be collected. Although bullfrogs will take rodents, they should not be fed mice regularly, as such has been shown to cause digestive problems.
Plan ahead if you decide to keep bullfrog tadpoles, because the adults require considerable space and care. If you do not intend to keep the frogs, arrange for a suitable adoption. Introduced populations of bullfrogs have caused considerable environmental damage, so they should never be released outside of their home range. Also, if you have purchased bullfrog tadpoles from a pet store, be aware that they have likely come from the southern part of the United States and may not survive the winters in the North if released.