Obesity

[andyroo]

One sometimes sees a fish, particularly a Botia/loach, that is obviously overweight and overfed. This recently dead monster carp in the UK, for example.
Fish are of indeterminate growth, more or less. Why do they not grow rather then fatten excessively? Even smaller loaches can have this.
Same in reptiles, particularly snakes in boring or small cages.
?
A

[Diana]

Good point. Perhaps because no matter what the nutrition (Calories, vitamins, minerals...) the cells can only divide just so fast. If the food comes in faster than the cells can make use of it to divide than the fish will store it as fat.

Remember that in nature fish can have periods of near starvation in between bursts of very rich feeding. They are designed to be able to eat a whole lot when the luxury amount is available, then can survive the lean times by living off their fat.

When a fish is in an aquarium with regular meals they will tend to put on fat. Less exercise, luxury eating all the time. This is part of the reason for feeding very small amounts of food, and skipping a day of food once a week. Obese fish are sick, with fat invading the internal organs and can eventually kill the fish.