Fish

Fish (also known as kaluun or malaay) are aquatic vertebrates that typically breathe water through gills—organs that extract oxygen from water. Most fish have fins for movement and swimming, and their bodies are covered with scales.

Fish do not form a single complete group (excluding birds, mammals, and other descendants). They are divided into major categories: bony fish, cartilaginous fish such as sharks and rays, and an older group such as lampreys that lack jaws. The number of known species is in the tens of thousands, making them the largest group among vertebrate animals.

Body structure

The fish body is typically elongated and compressed laterally, which reduces water resistance. Fins are distributed along the back, tail, belly, and sides; the tail fin typically provides most of the propulsive force. Bony fish possess a swim bladder that helps them maintain depth in water without excessive effort. Another important structure is the lateral line, which senses vibrations and water movement.

Habitat and diet

Fish are found in oceans, lakes, rivers, streams, and ponds. Some species can tolerate both fresh and salt water, while others such as salmon migrate to rivers to spawn. Diet varies widely: some feed on microscopic aquatic organisms (plankton), some on sea plants, and others are predatory on other fish.

Reproduction

Most fish produce many eggs that develop outside the body; males and females release eggs and sperm into the water at the same time. Some smaller species have live birth or retain eggs within the body. The number of eggs is large because only a small percentage reach adulthood.

Human use

Fish are a major source of protein, fat, and minerals, and form an economic foundation for fishing and maritime trade. Somalia has an extensive coastline along the Indian Ocean and Red Sea, where species such as tuna and shark are found. Globally, overfishing and environmental change have reduced populations of certain species, leading to regulations on fishing seasons and methods.