The Anatomy of a Fish - Fins

The Anatomy of a Fish – Fins

According to scientific resources, fish have been around for as long as anyone can remember. They have been roaming the earth’s waters for as long as 450 million years. During which they have constantly evolved to adapt to and survive in changing environments.

By becoming familiar with the physical characteristics of fish, you will become better at selecting fish that are healthy, spot problems more easily, recognize disease earlier, and, in general, become proficient aquarist.

Let’s look at the important parts of the fish – fins, which help fish navigate in the water.

The Real Submarine
Fish are equipped with at set of fins, six or seven of them, depending on the species. Through evolution, these aquatic creatures have developed to become the real ‘submarines’; in contrast, even when equipped with swimsuits or flippers and diving paraphernalia, we humans appear awkward in comparison.
Different fins serve different functions, and the combined effort of all fins is what propels a fish so smoothly and effortlessly through the water.

Dorsal Fin
The dorsal fin is probably the most prominent among various types of fins. When we eat shark’s fin soup, there’s probably some dorsal fin in the mix, and the dorsal is also a tell-tale sign of an approaching shark.

This fin is located along the back of the fish between the tail fin and the head. Its main function is to provide lateral stability, which makes it easier for a fish to swim in a straight line. Controlled swimming is a great energy-saver, and any fish that cannot swim well won’t live for long, since it would have trouble competing for food or escaping from danger.

Certain types of freshwater fish, such as certain varieties of goldfish for example, do not have dorsal fins, and are thus relatively clumsy fish.

Tail Fin
The tail fin, also known as ‘caudal fin’, is used to propel the fish forward. It is responsible for bursts of speed and fast swimming patterns. Fish also use this fin or retard forward movement and make turns.

Artificial breeding has, unfortunately, produced many species that are hampered by unnatural caudal fins; some ornamental fish have such excessively lengthy and oddly-shaped tailed fins that they struggle merely to stay upright.

Anal Fin
Located at the underside, between the pelvic and caudal fins, the anal fin’s purpose is to provide stability – it prevents your fish from rolling over.

Pectoral Fins
These fins come in pair, and are at the bottom, directly below the gill openings. Pectoral fins provide stability during movement, hovering and slow turns.

Pelvic Fins
Pelvic fins (also called ‘ventral fins’) assist the fish in braking, stabilizing, and changing direction. They are located in front of the anal fin on the abdomen of the fish and are also used for carrying eggs, searching for food and fighting.

Adipose Fin
A few species of fish – such as tetras, some catfish and members of salmon family – have extra fin on the back, in between the tail and dorsal fins. Much like the appendix in humans, the purpose of the adipose fin is not clear, but it’s probably there for some reason, just like our appendixes are.