Guppy fry with long black poop

[GuppyNewbie]

Hello everyone,
My guppy fry are experiencing long black poop. Is it normal or they are sick? I only feed them once a day with either frozen baby brine shrimp or daphnia or first bites hitaki.

 

[BigJfish12]

That looks normal to me

 

[GaryE]

It's not pretty, but it's pretty normal.

 

[GuppyNewbie]

It's not pretty, but it's pretty normal.

That looks normal to me

I did some research on the internet. Do you guys think I might need to add some algae wafer to their diets?

 

[GaryE]

I always gave me guppies some plant/algae based flake, in my mix of foods. Wafers, no, because they are large.