The web uploader looks for species names in the metadata and file names of the media you add and tries to match it to a species in the iNat database, then enters it as an ID. Computer vision isn’t activated unless you actually click in the species guess field.
Do you include fish names in the file names or keywords of your fish photos?
Are you talking about the suggestions that iNat gives in the uploader? Or are you saying that the iNat automatically fills the species name without your selection?
OP is describing a feature of iNat uploader, that was described by @tiwane, system reads the name of file you upload, and compare it with names it has in the database, filling the id.
Thank for your answers ans excuse me for this late reply.
Indeed, I name my photos of fish.
example: Marshall_Majuro_Maj1_Chaetodon lunulatus_4738.jpg
If I understood correctly, iNaturalist recognizes the taxon written in the file name and identifies my sighting with this info thanks to the functionality described by @tiwane
Thanks for your help, this settles my questioning.