I have tried all of that. Brine shrimp water, bloodworm water, tank water...brine shrimp flakes, first bites, bugbites....frozen bbs and daphnia....If you've been feeding them BBS, right now they just think if it's not moving, it's not food, it's all they know.
If they are too big for first bites, grinding up flake really fine will achieve the same purpose but be bigger particles, the idea is basically to get them used to the idea that some things that don't swim are also food.
Start with the first bites if you can if they are still small, soaking it in tank water is crucial to get any fry to eat it unless you get extremely lucky. if it's put in dry it floats on top, if you soak it for a couple seconds before adding it to the tank it will suspend, and if you squirt it with a pipette or syringe type thing it will swirl around as it suspends and they will usually take the hint and start hitting it.
my opinion if they are a month old, skip the first bites if you can and finely ground their flake or pellet or whatever you intend to put them on later, mixed in with feeding the bbs, and get them used to what they will be getting. don't bother with bug bites or daphina give that to them when they are bigger and more open to things that aren't moving being food, just worry about getting them on their regular staple food for now. you get that done, the rest just kind of falls into place. If selling or giving away, train them for the common foods people feed, so they aren't particular or picky for their new caretakers.
I found hatching bbs to be work and a mess. I had no patience for it. soaking first bites and then squirting some to the fish with a pipette was by far the quickest method to get them to eat it out of any of the other methods I tried. they took to it right away where other delivery methods failed.
If you use a pipette to feed the bbs, they should associate the tube with food and should hit whatever sprays out of it. then it's just getting them adjusted to it, they might spit it out at first expecting the bbs. but they will get used to it and learn it's food too.
You can feed a small bit every 2-4 hours or so, so they always have something and alternate between BBS and first bites each feeding. that way you can see if they are eating the first bites or not. and tell when they start taking to eating it and then transition out of the bbs,
But gonna say if the goal is to get out of bbs completely and the first bites eventually, (lets face it, first bites are small, the fish need bigger and bigger foods as they grow to gain mass and size) My opinion it's best to finely ground what their last staple food will be and get them used to that so you don't have another transition to make again later, and just don't grind it as much as they get bigger until you aren't grinding it at all.
I wish you the best of luck and a smooth switch over. it takes a bit for them to adjust.
my angels did the same thing, but stick to one food, the staple food you intend to feed and alternate when they are adults, just ground up. they will get used to it in time. You can vary it later on with other things.
Yeah I tried that the first week and it just sat on the bottom. I have been trying everything. The flake food I have been trying is the Cobalt brine shrimp flakes. Supposed to be for picky eaters.With my rams I strain my bbs in the net and on top I add a small quantity of golden pearls 100-200 microns and in the tank I mix the two on top of the water line and squirt with pipet. Eventually they get it just got to do both until they do. You can do the same with bbs and first bites.