My group of Geo. Red Head Tapajos don't bother anything and are a constant source of amusement. They're too busy sifting and spitting all day If I'm remembering correctly, the tetras stay at the top part of the tank. You may want to consider some floating plants as cover for your tetras. Unless its feeding time my Geos stay near the 'floor' of the tank.
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As mentioned aboved I have an 7/8 inch Satanoperca Lecousticta with some tiny (under an inch) harlequin rasboras and he shows no interest in them at all. I also have a 4inch Satanoperca Jurupari who isnt interested.
If your Satanopercas are anything like mine you will be fine
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Those are for sure satanoperca, but that isn't the best picture. I would say the species is either mapiritensis or jurupari(some jurupari have spots on the cheeks). Either way, your tetras will be fine as stated before. I have mapiritensis and no issues except amongst conspecifics.