Why do som Bichir have external gills

All juvenile bichirs have external gills and lose them as they get older, some just keep them longer than others but they eventually lose them.

They all have them at some point, but some tend to loose theirs earlier than others and some other tend to loose theirs later, but it's isually only juveniles that have them so the one you saw probably isn't a full grown adult

Maybe because their babies evolved to cope with comparatively low oxygen environments, such as warm water that isn't moving a whole lot. Bichirs aren't exactly fast moving arctic fish and increasing surface area under the operculum/gill cover is fairly tough if it's packed full so external gills can help. This is fairly consistent with air gulping seen in adults, which may also live in less than turbulent warm water. Source: Just a shoot at the hip take by someone who works in paleontology and has a relatively passable knowledge on evolution and how comparative anatomy can relate to it.

For the record: cold water has a higher capacity to house dissolved oxygen and the reason you want moving water is for increased surface area for oxygen to dissolve in.

Also note that external gills in aquatic amphibians are probably more the result of the skull becoming less kinetic, even compared to bichirs which are comparatively very immobile to telostei and other more advanced fish. That's a whole other thing though.

Also: A search on youtube for adult bichirs with external gills yields nothing.

I was largely comparing them to situations with salamanders, many of which have external lungs as infants and some of which retain them into adulthood. They tend to spawn in rather low oxygen warm water. It's just a plausible explanation for why you would need external gills, it dramatically increases the oxygen uptake rate.

Also why is a bichir keeper feeding bichirs to other bichirs? I bet he's a breeder doing a cull there.

Was that a bichir or a loach looked kinda loachie to me.

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Ponera said:

I was largely comparing them to situations with salamanders, many of which have external lungs as infants and some of which retain them into adulthood. They tend to spawn in rather low oxygen warm water. It's just a plausible explanation for why you would need external gills, it dramatically increases the oxygen uptake rate.

Also why is a bichir keeper feeding bichirs to other bichirs? I bet he's a breeder doing a cull there.

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Those are weather (dojo) loaches for sure. Never heard of them being used for feeders though.



Delhezi bichirs seem to keep their external gills the longest. It can be normal but it can also be a sign of low oxygenation or poor water quality. I had a deformed delhezi that kept his gills for very long: I assume because it was easier than swimming to the surface for air.

baconmeupscotty said:

Those are weather (dojo) loaches for sure. Never heard of them being used for feeders though.



Delhezi bichirs seem to keep their external gills the longest. It can be normal but it can also be a sign of low oxygenation or poor water quality. I had a deformed delhezi that kept his gills for very long: I assume because it was easier than swimming to the surface for air.

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Yea id agree dels seem to keep them the longest, they dont seem to have very long gills though. And really anything happens in asia

Weeksii by far keep them the longest at least for me.