Why must amphibians use internal fertilization while many fish can use external fertilization?

The embryo is isolated within the female, which limits predation on the young. Internal fertilization enhances the fertilization of eggs by a specific male. Fewer offspring are produced through this method, but their survival rate is higher than that for external fertilization. The offspring develops in the female and is born alive. This occurs in most mammals, some cartilaginous fish, and a few reptiles. Internal fertilization has the advantage of protecting the fertilized egg from dehydration on land. The embryo is isolated within the female, which limits predation on the young.

Explanation:

Because fish "Breath" water.

Explanation: Fish tend to have easy access from the outside of their body to the inside of their body which is why they use external. Amphibians however, are not the same. They're just built different. They do not let things into their body as easily.

not sure if this is what you'r looking for eubacteria and archaebacteria