Internal Anatomy: Rainbow Trout .

As an introduction to internal anatomy, we will examine this Rainbow Trout. A good place to begin is with some basic obsedvations. Note the fishes distended abdomen.

The factors that might cause abdominal distension are eight F's. They are: fluid, fat, fetus (or eggs), flatus, feces, freaked- out cells (tumor), foreign object, or food.

catfish on scale

Upon opening the abdomen of this fish, we observe that it is a gravid female. Mature eggs have reptured from the ovary and are loose within the peritoneum. Also readily visable within the peritoneum is the dark triangular spleen.

The operculum has been removed to expose the first gill arch. Note the white cartilagenous support of the gill arch at the cranial edge of the arch. This is the location of the gill rakers ( not clearly seen in this photograph).
Open abdomen

Internal organs are revealed in this photograph. In this fish there are four gill arches, a number that varies between species. The transverse septum in front of the liver, which separates the abdominal cavity from the gill chamber and heart, has been removed.

Roll the curser over different organs to learn specific features.

Magnify by holding down the with the mouse botton and moving the cursor slowly