Fish Anatomy

Fish Anatomy

Fish Anatomy to me is very interesting. Tropical Fish have been around for millions of years. They have adapted over the years to live in their environment. The fish anatomy is quite amazing and have evolved to meet different types of habitats. Becoming familiar with their physical characteristics will help you purchase fish that are healthy and can help identify potential problems. This page will help you understand and identify the anatomy of a fish.

Dorsal Fin

The dorsal fin is located on the back of the fish located between the tail fin and the head. This part of the fish anatomy provides lateral stability so that your fish can swim straight. Have you ever watched a goldfish swim? They have difficulty swimming because they don't don't have a dorsal fin.


Caudal Fin

The caudal fin is responsible for sudden forward movements and very fast swimming patterns. They also use this fin to slow down and make turns. This fin also produces the majority of the overall power of the fish.

Anal Fin

This part of the fish anatomy is the anal fin. It's located between the pelvic and the caudal fin. The sole responsibility of the anal fin is to provide stability. It keeps your fish from rolling over and going belly up in the water.

Pectoral Fins

This part of the fish anatomy is the Pectoral fin. This fin provides stability as the fish moves through the water, hovers and makes slow turns. These paired fins are located near the bottom of the fish directly beneath the gill openings. They are also used for navigation and are always moving.

Pelvic Fins

The pelvic fins are for braking, stabilizing their bodies and changing directions. These fins are located in front of the anal fin on the abdomen of the fish. This anatomy is used for searching for food, carrying eggs and fighting.

Adipose Fin

This is an extra fin the species such as catfish and some tetras have. It's located on the back between the dorsal and tail fin. It's often known as an extra dorsal fin.

Pictus Catfish


The shape of the body makes fish very efficient while in the water. It's tapered at the head and tail and big in the middle. This allows the fish to slice through the water with little effort. The fish's muscle force is achieved through energy created by short fibers the run through the fish's entire body. The energy is transferred to the tail to provide locomotion. The caudal fin pushes all the water surrounding the body backwards which propels the fish's body in a quick forward motion.

Gills And Breathing

As you know fish need air to breath. Fish take in oxygen through their gills. They are lined with large number of blood vessels that help them retrieve oxygen. Gills retrieve 85 percent of the oxygen from the aquarium water. That's why water is so important. Water enters through the mouth and passes across the gills where the oxygen is extracted by the gills. The oxygen-depleted water is then quickly discarded.

Fish Eyes

Fish Eyes

Most fish have the ability to see in two different directions at the same time. This phenomenon is know as monocular vision. Fish can't focus both their eyes on a single object at the same time. They also have no eyelids and sleep with their eyes open. Most fish are nearsighted and can only see about a foot away.


Since sound travels much faster in water, fish do not have ears like humans. Their ears are composed of a simple inner chamber where vibrations are picked up from the environment and passed over sensory components, which generate sounds. Some experts believe that the bladder works together with the inner ear to distinguish specific sound patterns.


Fish do smell and can detect food and prey and a mate. They take in smell through their nostrils which are connected to their olfactory system.


Fish have taste buds in their mouths, lips, and some have them on their fins. Their taste range is very short so they must constantly forage through their environment in hopes of finding food. Catfish have taste buds in their whiskers which helps them locate food in murky dark water.

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