A fish is an example of an aquatic animal; this simply means a type of animal that lives in the water. While reptiles can live in the water as well as on the land. Both types of animals are cold-blooded, and both are covered with scales except for cartilaginous fish that doesn't have a scale. Examples of reptiles are crocodile, alligator, lizard, etc. One of the major differences between a fish and a reptile is that a fish makes use of the dorsal and ventral fins for movement, a reptile, on the other hand, makes use of its limbs for locomotion.
Another difference is that reptiles are both oviparous and ovoviviparous. They are oviparous because they are characterized by egg-laying which is developed and hatched outside their body, and they are ovoviviparous because they are types of animals whose eggs hatch inside their body. Fish, on the other hand, are oviparous
Fish are graceful, aquatic creatures that lack limbs with digits. They have fins to swim and gills to take oxygen from the water. Reptiles, on the other hand, are tetrapod animals and they are cold-blooded. The skin of reptiles lacks a dermal layer.
Fish breathe through gills, while reptiles breathe through their lungs. Fish have separate scales, and reptiles have scaly skin. Fish are water only creatures their whole lives, while reptiles live on the land their whole lives. Fish are not smart, but reptiles are quite remarkable and intelligent.