a) Members of class Pisces are commonly called fishes.
b) They are aquatic vertebrates. They can be freshwater or marine forms.
c) They have a streamlined body which is divided into head, trunk and tail.
d) The body is covered by an exoskeleton composed of dermal scales.
e) Paired and unpaired fins help in locomotion. Pair fins help in balancing.
f) Respiratory organs are in the form of gills. Gill slits may be exposed or covered by
operculum.
g) They are cold blooded animals. Heart is two chambered with one auricle and one
ventricle. It receives and pumps only de-oxygenated blood.
h) Nervous system is well developed with a brain, a spinal cord and 10 pairs of cranial
nerves.
i) They are oviparous animals. Fertilization and development is external.
j) They can be cartilaginous fishes or bony fishes based on the composition of
endoskeleton.
Ex: Shark, Ray fish, Hippocampus, carp, Labeo etc