PlanetCatfish.com

- is not Hypoptopoma - fish by photo has no adipose fin.
May be and is the same fish?

Sounds plausible to me. I can't fix it tho', and I'd like one of the Hypoptopominae experts to confirm.

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Mats

According to Aquino & Miquelarena (2000), in their description of Hypoptopoma inexspectata, adipose fin is "variably present", ie some individuals have small adipose fin, some merely have a tuft of odontodes, and some lack it completely.
In short, presence/absence of adipose is not diagnostic for Hypoptopoma.

I am unclear on exactly what is the difference between Nannoptopoma and Hypoptopoma is (I think it's something to do with how exposed the pectoral ventral plating is), but the lack of an adipose fin on its own means nothing, and the fish looks like a Hypoptopoma.

I suppose it is possible that H. sp 4 and Nannoptopoma sp. Peru White is the same species at different age, I don't know.

They're not the same thing, and I have elected to keep them separate.

Jools