Water Fleas?

Do these look like water fleas? My 15g pleco tank is covered with thousands of these things. How do I get rid of them? Do I have to empty and clean the whole tank out? Never had them before.

I have the same thing in a 10g pleco.snail tank. Im not sure where they came from, but I cant get rid of mine either

Well remembering that Bettas are carnivorous I put three female Bettas in the tank and they seem to be eating them. I'll let you know in a few days how it's going. They should eat all of them. I have done this before when I had white worms in a tank and the Bettas got rid of them in a few days.

mine seem to be down in the gravel. Im not sure where they came from, but I just kinda forgot about them.

Mine is a bare bottom tank so I can see them all over the place. Since I put the 4 Bettas in though I think there a few of them less but it will take a few days to get them all. On top of this the plecos decided to lay there first batch of egg in there which I have been waiting three years for. They are in a cave with the male so I think they should be ok until I take the Bettas out.