It is a humanoid with silvery scales, sharp gills, webbed hands and feet, a sharp webbed crescent on its head, and fringed-ears on its head. This creature has been docile most of its life, but has been known to attack trespassers. This 5ft. cryptid is best known for its attack on two teenage children.
In comic #47, there were two Thetis Lake Monsters; a male and female. They were guarding their nests, but were attacking local residents. The local trout were carrying saprolegiaceae mold that harmed their eggs and kept them from hatching for years. The Saturdays ended up relocating them so that they wouldn't be hunted or extinguished to extinction.
This creature has an omniverous diet of underwater plants, small aquatic life, and a few land-based life. It is unknown is this creature seen the teenagers as food or violators of territory. They most likely were defending their boundaries.
The thetis lake monster has a behavior of scaling ranges. It can be very peaceful and quiet, or it can be very predatory and protective, All caution is to be taken when approaching the lake. In comic #47, they were highly protective of their nests. Their species is critically endangered and the Saturdays had to relocate them to safer, noncontaminated waters. The contaminents were harming their eggs.