The "trick" you need, is to not buy the cubes, which are handy if your have enough fish to consume all of one at a single feeding, so I' won't knock them out of hand.

Get a solid package of frozen brine shrimp and transfer the frozen block to a quart sized, heavy freezer zip bag.

Make sure it's rock hard frozen, then in the zip bag, lay it out on a wooden cutting board and go at it with a mallet, to break it up into many tiny bits.

You can also break it up inside the wrapper it came in, but I have found the original packaging too thin and easily split to survive the the mallet treatment.

Actually, as much as my fish love brine shrimp, I have gotten away from feeding them a lot, ever since I discovered Golden Pearls. No waste, size matched to fish, and consistant nutritional properties.

I haven't tried the frozen brine shrimp but feed frozen bloodworms and some daphnia. I get those cubes. I just take a frozen cube, and I swish it around in their tank water until enough of them come off the cube. Then put the rest of the cube back in the package and the entire thing in ziplock goes back in the freezer. If you don't mind touching the food this is very easy to do.

There is no perfect way but a couple of altenatives would
be to use a small dip net and rinse the cube in a cold water stream from the faucet (hand under the net) or use a
small dish to thaw the cube in a small amount of water. Then use a eye dropper to suck up shrimp only. These
methods seem to lessen the amount of filler and junk going
into the tank. Tank size and animal load seem to suggest
perhaps only using a half cube.

If you can find them Freeze dried foods are usually better and cleaner. In the case of Brine shrimp, when its frozen the exoskeleton bursts, and most of the nutritional value is lost. I have not used it in over 15 years. I don't think Daphnia has much to offer either, I do raise some occasionally, but its not the best food around. Frozen Blood worms, and mosquito larvae another thing altogether, they both freeze well, and are very nutritious. The only problem with bloodworms is some people have had allergic reactions to them, and some of them have been very bad, so be careful. I have heard of some people being hospitalized from reactions from them. The Golden pearls have impressed me, something that is not easy, I've been keeping fish for most of the past 45 years, worked for a couple of wholesalers, and owned a Pet shop. I'm currently raising groups of Killifish fry using them and newly hatched brine shrimp, and see very little difference between them, but I want to see how the fry color up. I am impressed so far, the Golden Pearls are easier to use,and would be perfect for those unexpected spawns that catch you off guard with nothing to offer fry for their very important first meals. I like the variety of sizes they come in, and won't miss hatching brine shrimp and paying what I feel is too high a price for cysts.

I have a funny story about frozen shrimp brine. I have this very old, very large feeder gold fish that I bought for the kids 10 years ago. When I drop the whole cube in the tank he will (I do not lie...hehe about this anyway) grab hold of it and not let go until he gets the entire thing in his mouth. I dont know if its a possibility but Im afraid one day he will drop dead from choking.

I have seen this same sort of behaviour in predatory fish
like Groupers and Lion Fish (saltwater) and Oscars (fresh)
I suppose the cube melts to a more manageable size by the
time they get it all the way in the gullet but I've had
cause to wonder myself.

I have a 20 gallon tank with 3 danios, 2 platys, 3 tetras, 2 cory cats and a rubber-lipped pleco. Every one of my fish go absolutely nuts for brine shrimp. Since I began feeding it to them, I take a tall cup, fill it about half way with water from my tank, drop an entire cube in, wait a couple minutes for it to thaw a little, then slowly pour the water in over about a minute and a half or so. The cats love it so I usually don't have much left uneaten at the bottom.