how do i get rid of the algae, my people need food

That's one of the puzzles to be solved in the game. If you need hints or solutions, you can find them in the Guides Section.

Let me tell ya...you have to be pretty patient...and watch your people like a hawk to finally accomplish it!

i got level3 farming and my master farmers or scientists still wont find the algae eating fish in the pond, WHY???

Are you dropping them in the pond? And are you sure that your farmers are not afraid of fish? One more thing...Do your farmers know that the algae is there? Have you tried dropping them in the ocean, then the pond.

You gotta make sure they like the fish and maybe you need to pause your game and shut it down then reopen it and try again make sure they have that they found the algae eating fish in their actions bar under their name.