Dear Amir

I have used Visceral Somatic Index (VSI) to basically investigate how much material (normally we are particularly concerned about fat) is deposited in the viscera, rather than in the muscle (the edible part of the fish).

What you measure exactly is really dependent on your needs, but from an economic point of view, a farmer is interested in what the yield will be from a whole fish to a gutted fish.  So, I would suggest to remove all of the viscera from the body cavity, including the kidneys and also the heart.

Measuring this will give you the VSI and also you can calculate the gutting yield (gutted weight divided by live weight), which is important to fish farmers.

When you report your work, state clearly what you did remove of course.

I hope this helps you a bit.,

best regards

Dave

Visceral somatic index, as I used to Pantanal fishes was calculated as viscera weigh (that means all viscera including also fat deposits in the viscera that is very high as a result of fish feeding  and accumulation during the flooding period). In catfishes, they have also a exclusive fat deposit in the abdominal cavity that has no similar in scale fishes. So, visceral somatic index is very important as we consider that a lot of Pantanal fishes do migration to headwaters for reproduction. If they don't have enough fat deposit (that can be measured as visceral somatic index), they doesn't do upstream migation for reproduction.

Visceral somatic index should be calculated as:  VSI = (Total weigh of all viscera / total body weight of the fish prior to removal of the viscera) * 100.

Es adecuada la recomendación de Timoteo L Hoffnagle.

La acumulación de grasa en las vísceras en peces esta relacionada con la maduración y crecimiento de las gonadas. Es importante registrarlo en relación con el índice gonadosomático GSI.

What exactly does not include the visceral weight in fish. I mean does this include also the gills?

Viscerosomatic indices calculated as viscera weigh in fish. Viscera weigh does NOT contain gills.