Hapawai snails clean brackish tank

I just got nature’s equivalent of a window cleaner! Excellent!

My friend Annette Tagawa gave me three hapawai snails (neritina vespertina), which are brackish water snails that eat algae. (http://dlnr.hawaii.gov/dar/habitat/streams/native-animals/)

She is a marine biologist. I love knowing her since we share a decapod hobby. We raise opae ula.

She and her colleague, Mike Yamamoto, wrote a book that includes information on the hapawai. According to “Hawaii’s Native & Exotic Freshwater Animals,” they’re not uncommon or endangered. 

They live at the lower end of streams, near the estuaries, and attach themselves to rocks or anything solid. They lay their eggs on the rocks, and after the eggs hatch, the larvae wash out to the sea, grow for a few months, then return to the stream.

They’re endemic to our state and their name means means “half-freshwater” – a reference to the half-fresh, half-ocean water environment it lives in. They also go by the name hapakai.

Annette came over and noticed my three tanks are full of algae, so she brought me some brackish snails so I can actually see into the tanks again.

The snails surprised me with their clam-shaped appearance. Their shell flares out at the bottom, which to me looks like a stingray. They can grow up to one inch wide. 

I guess I won’t have more than one snail per tank, because Annette pointed out, “If a snail gets big enough to produce eggs, not sure if they will survive in the tank as the larvae need to spend that portion of their life out in the ocean for a few months before returning to the stream. It’s not truly freshwater in the sense that it can’t complete its entire life cycle in freshwater only- all native stream animals are known to be amphidromous where a part of their life is spent out in the ocean and eventually migrate back to a freshwater environment.”

The hapawai won’t eat the opae as they are algae eaters. “If the opae were dead, maybe they’d feed on them opportunistically, but not a major part of their diet. Actually, any snail that eats algae and can tolerate brackish water will work in your opae tank to keep it clean."