Your very lucky , the best i get are snails ; My dwarf puffers love them tough , i managed to save a baby who lives in a separate tanks called Norman!
Where i live celestial pearl danios sell for nearly £10 and are really hard to come across !
I expect if there were any fry on plants my puffers would devour them in minutes ... shame
Love puffers, so cute and full of personality.
(Where in the UK are you? I travel to Essex every summer)