What exactly do they eat?

[ssdarling]

I know they eat the biofilm on things in the tank, as well as any algae growing on the glass. Do they actually eat the macro algae/cheatomorpha? Or is it just for the purpose of absorbing nitrates?

[Dch48]

I don't think they eat the macro. They do pick the other microorganisms off of it though and yes it does seem to absorb the Nitrates.

[Arnold]

They eat any decaying organics so they can eat dead macroalgae, in the wild the opae ula eat dead bugs that fall in the pools, leaf litter, etc

[DrKirk]

“Feeding cheliped setae are of two types, serrated setae that scrape the substrate surface and filamentous setae that collect the loosened food materials or act as filters. The shrimp are primarily microphagous grazers that scrape the surface of the algal-cyanobacterial crust on pool substrates. This grazing activity is essential in maintaining the integrity of the crust, an actively growing matrix of plants, bacteria, diatoms, protozoans, and underlying siliceous and carbonate materials.” - Bailey-Brock JH, Brock RE. 1993. Feeding, reproduction, and sense organs of the Hawaiian anchialine shrimp Halocaridina rubra (Atyidae). Pacific Science 47(4): 338-355.

https://scholarspace.manoa.hawaii.edu/handle/10125/2024

[Mustafa]

On very, very rare occasions these shrimp even filter feed. They'll sit on the sides of the tank and "grab" the water repeatedly to filter out microorganisms. These are truly very versatile shrimp. .