I edited your pic to get a closer. look
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But still not great for an ID, so here are a coupe comparators
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Above are a couple from the Uruguayan saxitillus clade.
Below a belly crawler
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There are over 75 separate species of pike cichlids, in 4 diffenet genera from east of the Andes in S America.
There are cool water species from Argentina and Uruguay, warm soft acidic water species from rivers like the Riio Negro and Orinoco that require low pH, and, and many inbetween