can you think of any fish, whose diet significantly changes over their life span???

[Magnum Man]

so, I think most fish are omnivores, I know there are physical differences between mostly plant, and mostly meat eaters... I thought of this question, watching the dining habits change in my Hillstream tank, from young fish, to adult fish... these all being algae / biofilm eaters, but some seem to change their preferred spots to eat ( I assume there are slight differences in the algae or bio film composition, between, for example, what grows on roots, and what grows on flat surfaces at the top of the tank, under the lights...

... and I'm sure there are species that start out eating mulm , as fry, that become solely carnivorous through the bulk of their lives...

... wondering if as they age, like many humans, they lose the ability to chew their food, like that big beef steak, or the ability to digest it, and end up eating bland baby food like humans???

 

[Back in the fold]

An interesting question to be sure but I think almost any fish would naturally or unnaturally expire before they were ready for graveyard stew .

 

[gwand]

I still like pizza even after 72 years

 

[WhistlingBadger]

Well, brown trout start out eating insects, and get increasingly piscivorous as they age. And I know of at least a few fish (chinese and siamese algae eaters; I'm sure there are others) that start out eating biofilm and become more omnivorous or even carnivorous as the get older.

 

[Colin_T]

Virtually all baby fish eat single celled algae and microscopic organisms before graduating onto fish & crustacean eggs, shrimp & fish larvae, and tiny insects or insect larvae. Throw in some small worms and that is their baby diet.

After they have grown they will still eat some of those things but usually eat the bigger versions of them including macro algae & aquatic plants, fish, crustaceans, insects & insect larvae, worms, and anything else that lands in the water.

Discus and Uaru babies eat the mucous coating off their parents for the first few weeks before moving onto small organisms in the water, along with algae and plants.

Fish are opportunistic omnivores and will eat pretty much anything edible that fits in their mouth, a bit like people

 

[GaryE]

A lot of Loracarid catfish start out eating algae and the creatures that live in it. We buy them as algae eaters, but as they gain size and ability, they switch to plants and we're stuck with honking big fish that wreck tanks and don't bother with algae anymore. That's another call to do some research first...
I start my little insect eaters on freshly hatched brine shrimp, and most of them will eat that food for all their lives - it's small but they can catch it.
I don't know of any fish that 'step out of their anatomy'. If they have the guts of a plant eater, they may switch sources as they grow. If they are fruit eaters, they have to adapt to aquarium foods or die, but that's not a natural shift. If they need roughage from insects, or high protein, or other fish, we can sometimes change their ways, but again, it's their anatomy and its natural history behind that, and fishkeepers can sometimes ignore that.
If you keep Scatophagus (poop eaters), I'll bet you change their diet fast. But you do that - they don't.
I think a lot of it is just size. Bigger creatures like bigger foods.

A lot of fish have throat and roof of the mouth teeth that regenerate as they go along. They don't lose teeth like we do - the poor things have never learned to play hockey like Canadians.

 

[simonas]

My fly river turtle as a juvenile eats a more protein based diet but now that he is growing I am trying to get him on his main diet which will be fruit based but its not going so well as he much prefers frozen fish and protein bug bites to grapes and blue berrys

 

[WhistlingBadger]

My fly river turtle as a juvenile eats a more protein based diet but now that he is growing I am trying to get him on his main diet which will be fruit based but its not going so well as he much prefers frozen fish and protein bug bites to grapes and blue berrys

I can identify. I prefer elk to salad.

 

[anewbie]

I can't remember the species names but there are several freshwater fishes that migrate as they age and their diet changes quite a bit. I think in nature discus diets also change significantly as they age. there are several species that require salt or brackish water to breed but otherwise live in freshwater that have unique diets.