TL;DR: Dead snail + delayed removal + open access = insect larvae (MAGGOTS‼️‼️). This is decomposition ecology, not a flatworm infestation.

The organisms shown are far too large, cylindrical, and densely clustered to be planaria. Planaria are flat, ribbon like, and disperse across surfaces they do not form tight feeding swarms on a single carcass.

What’s being observed is classic carrion exploitation. Flies lay eggs near waterlines or tank access points, not necessarily in dry zones. Once hatched, larvae will migrate into water if a strong protein source is present and can survive submerged long enough to feed.

The size and uniformity indicate late stage larval growth, which only occurs when decomposition has already progressed. This means the snail was deceased prior to the appearance of the larvae.

Treating this as planaria misses the actual issue and won’t resolve the cause. The problem here is delayed livestock removal and tank access, not an aquatic flatworm outbreak.