Black military helmet nerites have not moved in WEEKS
Around mid December I bought four milltary helmet nerites from my lfs (reputable place in Portland). They seemed to move around quite a bit for the first two weeks or so, but they have not moved in almost a month. I have taken each of them out two or three times to smell them and check the trap door. Trap doors are firm and there is no smell at all.
A few weeks ago I did notice a few dragonfly nymphs in my tank when I saw one biting one of the nerites. I pulled all the nerites out and put them in a 1g jar for a few days while I scoured the tank and killed every nymph I saw, and have seen none since.
Could the snails be hiding in fear, not aware the nymphs are gone?
I've read that they can hibernate for a several days, but this seems odd.
Tank is 20g, heavily planted, and has about 20 celestial pearl danios and 15 orange Sakura shrimp which are all thriving. Around 10-15ppm nitrate (i fertilize every 2 days), 0ppm nitrite, 0ppm ammonia. Water is naturally soft here (2-3 TDS from tap), but I mineralize to about 120 with salty shrimp. Ph is usually 6-6.5.
Any insight or advice is welcome and appreciated!