What is a baby fish called?
The newly-hatched fish is either called a larva or hatchling - to be honest, we guys at the shop, working with fishes all day long far preferred the endearing ‘hatchling’ to the more technically accurate but cold ‘larva / larvae’.After a few days, newly-hatched fishes will use up their egg sac and become not just free-swimming but hungry babies. This is the stage at which they are called ‘fry’. When the fry stage ends is an open-ended question, with no satisfactory answer, but once you can see adult-type colours and body-form showing (which the young fry typically do not for several weeks depending on species), then it’s no longer a fry.The term ‘fingerling’ is used in fisheries for younger pre-adult fishes which are past the juvenile stage and (funnily enough) about the size of an adult human’s finger (or thereabouts), but truthfully my experience has been with species which just don’t grow as large as that or as quickly. Most ornamental tropical fishes are adults by the time they are the size of a finger (if they even get that big), so we never ever used the term ‘fingerling’.Where Goldfish were concerned, we would occasionally use the term ‘yearling’ for the smallest fishes, hatched the previous summer and shipped to us from spring to autumn. This was by no means an official term, but we liked it and it worked for us.Other specific terms for babies include ‘parr’ and ‘smolt’ for Salmonids and ‘elver’ for eels.
What is the fish called? Peruna?
Piranha. (Or occasionally Piraña, which is a much less common spelling, but it's the same fish.) weird spelling, isn't it?
What are the fish that hang off of sharks called?
The ones that actually adhere to the sharks are remoras. They're fishes belonging to order Perciformes, family Echeneidae, and they have a dorsal sucking disk with which they attach to sharks , but also to other bony fishes, turtles or marine mammals. These fish clean their "host" and feed on their leftovers. This is what a remora looks like: http://www.amonline.net.au/fishes/fishfa... The other, more typical-looking fish with dark and light vertical stripes, are pilotfish. These also belong to order Perciformes, but to a different family, the Carangidae. Their scientific name is Naucrates ductor. They were called "pilotfish" because of the belief that they "guided" sharks. Actually, they're semi-obligate commensals of sharks, rays, other bony fishes and turtles, which means that they depend very much on them to feed on their leftovers. This is what a pilotfish looks like: http://www.horta.uac.pt/imagdop/Servicos...
What's the fish that sucks on the wall called?
Depends. You can call it suckerfish. Or you can find out which of the few dozen species that suck walls you got and call it by the proper name.