Hello Bill, I simply remove the water using thin silicon pipe ( I watch out for the young fishes) and then I tilt the container and I let the fresh water from the big tank comes in. From time to time I put out the container to see whats happen there , especially when I changed the food from protozoa to artemia . You can see attached pictures. Today I moved the first brood to the 10L aquarium ( 8 pcs – 2 died when I feed artemia first time ..) , hope they will grow faster. In the second container is 35 of fry ( I saw only one death from the moment I puted them there (1.5 week)).
Greetings!