It really depends on the species.
Not all tropical fish even lay eggs, guppies, platys, and swordtails are good example of livebearer tropical fish. So the number of eggs a tropical fish lays cannot be determined.
depends on the fish.
Guppies are live bearers which means they give birth to live fry. The average is 20 - 50 fry.
fish eggs and young fish tend to have many predators that want to eat them so many of them don't survive. By laying large amounts of eggs, adult fish increases the probabilty that one of those eggs will survive to grow into a full grown fish and reproduce.
Clownfish typically lay 100-1000 eggs in a single clutch, with an average of around 400-500 eggs per spawning event.
500 fish
It varies depending on the type of fish. For many, female fish lay eggs. The eggs are fertilized by the male fish outside the body of the female after they are laid. The eggs grow into baby fish.
This greatly depends on which species that you are talking about. There is no average because your question is far too general.
most of the eggs will not survive ...
None. Fish lay many eggs, only some of which become fish.
A female mackerel fish has been reported to lay an average of 50,000 to 300,000 eggs at a time. The eggs are laid by the female mackerel in the open sea.
clown fish lay so many eggs because the eat them