I agree yellowfin....they live in the area and the profile looks right. Why do you doubt that they are yellowfin?

Pompano?

Linda, I guess I doubted it because I did not expect to see them, and also they were rather small and did not have an additional dorsal fin that I expected, but they could have that fin flattened, or it could be less pronounced in juveniles.

Pompano is an Atlantic fish, and so it would not be found in the South Pacific.

It does look like this fish, however, and I have bought a lot of yellowfin tuna that was caught in Fiji. In fact, most tuna in southern California seems to come from Fiji. I just never expected to be swimming with a school of tuna, as I associate them with deeper waters. The next fish I saw after them was a small ray, and I got a good video of that.

I also didn't think it looked quite like yellowfin—my father used to catch them along California waters—so I googled up pictures. There seems to be a lot of variation to the shapes. Some seem to have hardly any dorsal crest, and others look amost like mini-marlin, Some are classic tuna shape, some are much rounder. Few seem to have that tail shape, but some might. Or it could be a Fiji thing.

Here's a photo of a yellowfin tuna in Fiji from a fishing site:

I think it looks pretty similar, although this is a much larger fish. Adults probably look significantly different from younger fish.

The shape of the tail is much more like what I think of for yellowfin. All of them in your own photo have the same shape. Could be a local trait or mutation from same parent. I don't think such a different shape would merely be juvenile, but I'm no expert. The body shape is more like your fishing site picture than classic tuna. None of this is definitive, either way.

I could send your picture to a diver I know for another opinion if you like.

Yes, please send my photo to a diver for another opinion. I was thinking that it might be something else, but I have very limited knowledge of what tuna look like in the wild.

The main difference I see in my photo and the fishing site photo is the tail, and I do think that this could be attributed to my fish being juvenile, but that is just my guess.

This photo from Australia looks more like what I saw.

Yellowfin tuna off Australia

I disagree that the tail shape is the same as the yellowfin's. The yellowfin's tail is almost straight, while the tails of the fish in the first photo are distinctly V shaped. Body shape of the mystery fish is shorter and broader, and the fin placement is a bit different.

The tail fin is one of the things that really threw me off, but I thought it might just be a variation of the same species.

It does look more like Dcarch's fish. I'll let you know what my diver friend says when I hear back.

That looks much more like it, and the description of how it moves closer to the beach also makes it seem more likely to be the correct ID.

I've never heard of this fish before, however, but it is a type of Pompano, and so Jim Mat may also have been correct. I now no longer think that they are tuna.

I got an ID from What's That Fish as Small Spotted Dart, which is the common name for Trachinotus baillonii. I guess that mystery is solved now.

Dcarch, did you post that info on What's That Fish?

Good going to What's That Fish! And to Dcarch for recognizing it right off. My diver didn't even answer the question. Just said some nice personal greetings and linked me to one of his videos, which has no identifications, just lots of reef denizens and practically no fish. Pffft. I do think he was just hurrying through his email, but a simple "I don't know" would have been more useful. ;) Thanks for "small spotted dart". Flora and fauna seem more real when they have common names.

I got more information about this fish from this site, and that would not have been possible if the fish had not been identified. It says that they occur near surface waters of lagoon and seaward reefs, and that exactly where I saw them. The fish nearer the beach were very different from the ones right on the reef.

It appears that this fish is also edible, since it is listed as having minor commercial use. I posted this on Cooking because I thought this might be an edible fish.

"---Dcarch, did you post that info on What's That Fish?---"

No I did not. I am not a member there.

dcarch

The diver sent another e-mail answering the question, but he didn't know, anyway. :D