Piscis lapis (Stone fish)
Common names: stoning fish, lapidation swarm, pebble school, hunting stones
Description:
Stone fish are small greyish polymorphidae that change their forms between fish and stone. In fish form they have a rounded and rather flat face, thick mouth layered with sharp little teeth, and six fins in addition to the tail fin. In stone form they are usually rounded and have a grey, rather rough looking exterior. 
When changing into stone form, Stone fish condense their body, therefore their stone body is usually a little smaller than their fish body. In both forms they have grey coloring with a dull silver glint, the silver is much clearer in the fish form, but some Stone fish have a silvery shimmer in their stone form as well.
by Peculiaris
Habitat:
Oceans, with a preference for warm waters. They are most commonly found in the Indian Ocean.
Diet:
Stone fish are carnivorous, and their diet consists mainly of other fish. Their unique hunting swarm technique allows them to feed on fish much larger than themselves, and would be enough to feed the entire school.
Habits & Culture
Stone fish live in shoals, the smallest include 20-30 members, the largest can reach over a hundred. The same shoal may fluctuate greatly in size around hatching season, as the hatchlings remain with their parental shoal until they are about a year old, at which time they reach adult size and can hunt and protect themselves. The young Stone fish then choose whether to remain with their parental school, or form a shoal of their own.
Stone fish reproduce by polygynandry spawning, in an area chosen by the shoal. During the summer months, as the water reaches higher temperatures, the shoal will locate a secluded area that they can easily guard. They essentially build a nest by lying close together, while in their stone form, creating a tight circular shape. Once the nest is arranged, the females of the shoal deposit unfertilized eggs in the soil at the middle of it, then the males will release their sperm to fertilize them. The eggs hatch in about 48 hours, but it takes 2-3 days before the larvae can swim and feed independently. The shoal remains close to their young throughout, until the eggs hatch the nest is kept constantly, so in small shoals the adults would often not move, even to eat, until the eggs hatch. Once hatched, the larva requires feeding, so the adults change between watching over the young and hunting for food for the shoal. The larvae usually stay in stone form, which makes feeding somewhat complicated, but keeps them safer.
Once the young Stone fish are able to swim, the shoal will leave the nest area and move about, keeping the young ones in the middle of the school for their protection. The young Stone fish enjoy playing together, tuning their shifting hurtling themselves at rocks and at each other, which sometimes has distressing results if they don’t manage to change form fast enough. After a few weeks the larger of the young are big enough to join hunting parties, before that their stone form is simply too small to be effective.
Hunting is the main way Stone fish get food, although they can feed on plankton and other small marine beings, their preference is to get a large prey that will be enough to feed the shoal. Stone fish hunt by pelting their prey to death; while in fish form, they dash towards their target, gaining speed, and then shift to stone form just before hitting. The momentum of the hit usually throws the Stone fish off some distance, where they shift again to fish form and begin again. The shoal coordinates the attack, and usually the hunt ends in a few minutes, with the meat of the prey softened from the pelting, and the shoal enjoying their meal.
Stone fish are deceptively small and delicate looking, and the few humans who encountered a shoal and deemed them ‘adorable’, soon changed their minds...
by Peculiaris
Once the young Stone fish are able to swim, the shoal will leave the nest area and move about, keeping the young ones in the middle of the school for their protection. The young Stone fish enjoy playing together, tuning their shifting hurtling themselves at rocks and at each other, which sometimes has distressing results if they don’t manage to change form fast enough. After a few weeks the larger of the young are big enough to join hunting parties, before that their stone form is simply too small to be effective.
by Peculiaris
Stone fish are deceptively small and delicate looking, and the few humans who encountered a shoal and deemed them ‘adorable’, soon changed their minds...
Piscis lapis
by
Peculiaris
Piscis lapis in fish and in stone forms.
Taxonomy Chart
Magion - Polymorphidae - piscis - lapis
Basic Information
Lifespan
7-10 years
Average Weight
250-300g
Average Length
10-12cm in fish form; 5-7cm circumference in stone form.
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