I know viejas can b very hard to id when small so ive been waiting to ask. My little guy is about 4 inches and i hope big enough for someone to help me id this little guy
At 4 inches most Vieja are very similar. Looks a bit like melanuris aka synspillum, but just for reference below is a 4" female breidhori
and a 4" bifasciatum
only sure way is to count fin rays and spines and match to a taxonomic key.
regani and argentea.
differences are very subtle at that size, and color in all is variable from location to location, so not a sure indicator. Melanurus can be red headed, or all yellow, as can be bifasciatum.
Looks like a juvie 'synspilum' from the reddish head and the broken bar (spots). My adults looked like yours when they were young. Here's a pic of a male 'synspilum and 'bifasciatum' for comparison.
I'd say about 80% sure Synspilum/Melanurus but it's pretty early to tell just yet. The color will probably start to come in within the next inch or two quite vividly.