Fish can have complex mating rituals, including courtship displays and nest building.

The stonefish is one of the most venomous fish in the world.

Fish can be solitary or social, with some species forming schools of thousands of individuals.

The sawfish has a long, flat snout lined with teeth used for hunting.

Fish can exhibit territorial behavior, defending their home range from intruders.

Some fish, like the guppy, can reproduce asexually through a process called parthenogenesis.

Fish can have a variety of reproductive strategies, including laying eggs and live-bearing.

The mudskipper is a fish that can walk on land using its pectoral fins.

Fish can feel pain and stress.

The gills of fish are composed of thin filaments rich in blood vessels.