Can you ACTUALLY overfeed your fish?

Latte · Jan 4, 2023

I've been wondering recently: can you actually overfeed fish?

Obviously I'm not talking here about overloading your tank with nutrients, or dumping in tons of food that the fish won't ever actually eat.

But, assuming you have the nutrient control/water change schedule to keep up with what you're adding so that the water parameters remain safe - is it possible to actually cause harm to your fish purely through them consuming too much food? If so, what actually occurs? Is it feasible that even the most heavy feeding aquarist could actually cause this?

Observing reef fish in the wild, many are much larger than those we find in tanks, and many are constantly eating. I'm sure that some would result from setting up a funnel and force feeding your tangs for hours every day - but it seems to me that as filtration advances, we can likely feed our fish many multiples more than we do now, and that they'd be better for it.

Jekyl · Jan 4, 2023

They're also in a much larger space and using far more energy would be my thought. Size being limited to being in a tank and food consumption lowered as getting far less exercise.

Spare time · Jan 4, 2023

Eh. I'd imagine they would stop eating if they were full based on my experience feeding fish. It's also hard to generalize all "fish" to get an answer. The only downside I can think of that would be universally true would be that metabolizing food creates free radicals oxidants which leads to shorter life spans. Hence why antioxidants are advertised to help prevent cancer as oxidants damage DNA. This is true across the animal kingdom. The faster the metabolism, the shorter the lifespan on average. However, I would not be concerned with this in our tanks.

Jekyl · Jan 4, 2023

@Lasse probably has some good input on this subject.

Lasse · Jan 4, 2023

Latte said:
I've been wondering recently: can you actually overfeed fish?

Obviously I'm not talking here about overloading your tank with nutrients, or dumping in tons of food that the fish won't ever actually eat.

But, assuming you have the nutrient control/water change schedule to keep up with what you're adding so that the water parameters remain safe - is it possible to actually cause harm to your fish purely through them consuming too much food? If so, what actually occurs? Is it feasible that even the most heavy feeding aquarist could actually cause this?

Observing reef fish in the wild, many are much larger than those we find in tanks, and many are constantly eating. I'm sure that some would result from setting up a funnel and force feeding your tangs for hours every day - but it seems to me that as filtration advances, we can likely feed our fish many multiples more than we do now, and that they'd be better for it.

IMO - it happens in nearly every aquarium. And IME wild fish is much smaller than fish feed in aquarium if they are of equal age. Its true that wild fish eat constant if there is food available - they must because in the next moment they have to starve because lack of food. Modern dry food is also 5-7 times more nutrient rich compared with natural foods

Sincerely Lasse

Brooklands · Jan 4, 2023

Latte said:
I've been wondering recently: can you actually overfeed fish?

Obviously I'm not talking here about overloading your tank with nutrients, or dumping in tons of food that the fish won't ever actually eat.

But, assuming you have the nutrient control/water change schedule to keep up with what you're adding so that the water parameters remain safe - is it possible to actually cause harm to your fish purely through them consuming too much food? If so, what actually occurs? Is it feasible that even the most heavy feeding aquarist could actually cause this?

Observing reef fish in the wild, many are much larger than those we find in tanks, and many are constantly eating. I'm sure that some would result from setting up a funnel and force feeding your tangs for hours every day - but it seems to me that as filtration advances, we can likely feed our fish many multiples more than we do now, and that they'd be better for it.

Best thing is to try to create a natural biome where they can pick at small critters all day and then just supplement feed. Doing so will enable you to leave your tank unattended for 2 weeks with no issues at all (assuming you figure out the evaporation rate).

revhtree · Jan 11, 2023

I’m the one who’s always afraid I’ve “underfed” so I end up over feeding! Not in the sense you are discussing though.

Enderg60 · Jan 17, 2023

I cloud feed my tank and I can tell you fish will stop eating when they get full. Might only last a few hours before they start eating again but it happens.

The only reason to limit food input is nutrient spikes in the tank. Fat fish are healthy and happy, you just have to match your filtration with your feeding.

The reason people say dont overfeed is because that usually led to water degrading FAST and the fish would die. This is mostly the case in goldfish and betas in a bowl.

Hell WWC says they feed every hour, and if you can thats a great idea. Less food is wasted, fish get fed more, and fish will fight less when full.

Rtaylor · Jan 19, 2023

Yes, you could shorten the lifespan of the fish by over feeding. Fish can be overweight, get fatty livers, etc. which would be detrimental to their health. I wouldn’t worry too much about over feeding, but it does have some potential negative consequences.

Rusty_L_Shackleford · Jan 19, 2023

Enderg60 said:
I cloud feed my tank and I can tell you fish will stop eating when they get full. Might only last a few hours before they start eating again but it happens.

The only reason to limit food input is nutrient spikes in the tank. Fat fish are healthy and happy, you just have to match your filtration with your feeding.

The reason people say dont overfeed is because that usually led to water degrading FAST and the fish would die. This is mostly the case in goldfish and betas in a bowl.

Hell WWC says they feed every hour, and if you can thats a great idea. Less food is wasted, fish get fed more, and fish will fight less when full.

Fat fish are healthy fish. I spent some time in aquaculture facilities and public aquariums, and you would not believe how much the fish get fed. The only reason to limit food is water quality. Ive always fed pretty heavily, but i also do a lot of water changes.