Never had that problem with my line of Blacks and I do not use the S.F. brand. Too pricey. I use the Salt Lake City Brine shrimp eggs. I feed bbs to my angel fries on their first day of free swimming.
I also breed Bettas and Gouramis occasionally. For their fries I use green Water for a few days before switching them over to bbs.
I maintain a tank of feeder guppies in my patio for my Arowanas. Their tank if left uncovered for a few days under the Florida Sun turns green. I just scoop water from their tank and pour it in the containers holding the small fries. I've also occasionally use this approach with Angel fries when I see that they are not eating the bbs in their first few days.
If you are not getting enough Sunshine to turn the water green, you may also use spirulina powder blended with water as feed for very small fries. I prefer the green water from my guppy tank because it has live algae and it won't foul up the fries' tank even if they don't eat all the green stuff.
I also breed Bettas and Gouramis occasionally. For their fries I use green Water for a few days before switching them over to bbs.
I maintain a tank of feeder guppies in my patio for my Arowanas. Their tank if left uncovered for a few days under the Florida Sun turns green. I just scoop water from their tank and pour it in the containers holding the small fries. I've also occasionally use this approach with Angel fries when I see that they are not eating the bbs in their first few days.
If you are not getting enough Sunshine to turn the water green, you may also use spirulina powder blended with water as feed for very small fries. I prefer the green water from my guppy tank because it has live algae and it won't foul up the fries' tank even if they don't eat all the green stuff.