There are more than 60 species of flying fish, commercially they are all simply called flying fish.
Much like tuna, there are nearly 50 species of tuna but only a small handful have specific names so aside from the bluefin, sailfin and a few others, most are simply "tuna".
Locals may have nicknames for them but these would vary from region to region throughout the world.
smelt
Tributaries
According to Wikipedia, The Great Fish River was given the name 'Great' to distinguish it from a river that was already called the Fish River in Namibia.
school
there is salmon fish and a type of fish called a copepod and another small fish called a gammarid.
Fry! They are tiny little black fish the size of a pinhead. Many baby fish are called Fry.
Well relatively speaking there are these tiny little "Water flea's" called Daphnia they are actually classified as a crustacean and is a very popular munch for baby fish
No. Krill are tiny shrimp, that swarm in open oceans by the billions.
corals (?)
deposition
the name of a tiny freshwater fish is a minnow
A tiny coral reef dwelling fish called a Pygmy Goby has the shortest lifespan of 59 days
A River Runs Through It