Dietary variety is the key to your pet amphibian's good health. In their native haunts, most amphibians are formidable hunters; the American bullfrog, for instance, routinely devours bats and turtles. Chinese giant salamanders have been known to eat ducks, and an African bullfrog was observed consuming 17 hatchling spitting cobras.
What to Feed
The vast majority of amphibians are confirmed live animal feeders. Captives take a wide range of items from crickets to earthworms, roaches and crayfish. Insects are the easiest to feed to your pet and the most readily available (live crickets can be bought at most pet shops) but they will have to be supplemented with vitamins.
First, make sure you buy insects of the proper size for your pet. Then, before the feeding, dust them with a vitamin/mineral supplement that contains calcium and vitamin D3. Calcium supplementation is particularly important in preventing metabolic bone disease, or MBD, a serious bone degeneration that happens when a frog gets too little of the mineral. Place the feeder insects in a small jar with a pinch or two of the supplement; cover the jar and shake it to coat the insects with the powder. These coated insects are known as "shake and bake" feeders.
To ensure that insects to not lose their vitamin coating, use food bowls or tongs for feedings. Secretive species such as red salamanders may not adjust to this, so feed them at night when they will consume the food quickly. Viewing lights with wavelengths invisible to amphibians are available and will help in the care of nocturnal species.
Insect larvae such as grubs and mealworms will provide good nutrition as well. (These wormlike creatures are the earliest stage of developing beetles. Use them before they develop the formidable jaws they'll have as adults.)
Earthworms and blackworms are nearly complete meals with no need for nutritional supplements. The earthworms in your backyard are fine so long as you know there's been no pesticide used. Put them in a bowl so the pet will eat them before they have a chance to escape too deep into the substrate to be found. Ads in reptile magazines sell a variety of worms and grubs.
On average, the smaller the food items the better since smaller prey provide a greater area for the action of digestive juices and, in the case of immature insects, contain few indigestible parts. While most amphibians expel any substrate swallowed with their prey, some can swallow gravel or moss, which may become impacted in their stomachs. Remove uneaten food before it begins to pollute the tank.
Again, check on the individual needs of your pet. Some have very special needs. Treefrogs, for instance, will generally feed only on climbing or flying insects and the red-eye treefrog will only feed at night.
Wild-caught insects should be offered whenever possible. You can buy a commercial trap or catch them by sweeping a net through tall grass. This will provide an excellent assortment of food items. You can sort these out for size by putting the appropriate size holes in the container in which you're holding them.
If you're keeping your own supply of insects, feeding them with fish food flakes sprinkled with the powder gives the insects the vitamins that the pet will need. You can also provide the insects with vegetables and fruits such as yams and oranges which will translate into more vitamins for your pet. This is known as gut loading.
Rotate type of food you present to your pet. A few different kinds of insects, worms and beetle larvae (mealworms, waxworms) are usually available at your pet store. Fishing bait stores often have earthworms, minnows and insect larvae called grubs. If you collect your own insects you'll have a more diverse diet to give your pet. It is not too much to vary the food you give your amphibian each feeding.
Rigorous Feeding Schedule
Try to maintain a regular schedule feeding the animal three times a week on average. Most will stop eating when they're full. Then remove uneaten insects. Check on the needs of your specific pet. Tiny active frogs such as mantellas, for instance, require daily feedings and frequent supplements while fish- and earthworm-eating salamanders such as sirens, do well on bi-weekly feedings with no supplements.
The metabolism of ectothermic (cold-blooded) animals such as reptiles and amphibians depends upon the temperature in which they're living. This means that the warmer the temperature of their surroundings, the faster their metabolism and the more food they will consume. At extremes of temperature, however, they will either stop eating or be unable to process the food. Most amphibians digest effectively at temperatures of 55 to 70 Fahrenheit, but certain species such as the dwarf underwater frog, require temperatures up to 80 F.
Feeding Young Amphibians
Amphibians go through a series of metamorphoses in their development from egg to larvae to adult. In their larval stage; think of a tadpole;
they are small legless water creatures and have to be fed more like fish. Like the young of most species, larval amphibians are voracious feeders. All salamander larvae thrive on blackworms; tadpoles of frogs will thrive on tropical fish food and finely chopped parboiled kale.
There are some carnivorous species of amphibians. The marine toad and horned frog will take pink or weanling mice and whole fish. Both are nutritionally complete. While in the wild, tiger salamanders can also eat a mouse; rodent meals in captivity can cause fat deposits called corneal opacities to develop in the animal's eyes.