Let me know if you see any shrimp or prawns (especially long-armed Macrobrachium). You'll find them beneath undercut banks, in submerged vegetation and roots, and under stones.
Im here in Lima already and will be going up to Iquitos on Monday. I have a shipment set to arrive in the US for Wednesday so let me know what you are looking for and i will get you pics. I do have some tiger rays available and some nice motoros. Pics coming soon...