So, you've got the fry in their tank. What do you do now?
You've got the fry tank set up right? Yeah... definitely forgot to go over that part first. A small 5 or 10 gallon tank works best.
It needs a heater. Put tape (black electrical tape is best) over the light. You don't want the fry attracted to it and die.
You'll also need some sort of circulation in the tank. You can't use powerheads because the flow is too high and it will chop up the little guys. The best method to get flow is to just use air bubbles. Stick the airline tube under the heater to disperse the heated water. As the bubbles rise, water comes up too. This will create flow in the tank. You can put air lines in each corner if you want, which is best, but most people just have 1 or 2.
That is all that is needed for the fry tank. Pretty simple huh? Now you have the tank set up and the fry in it. They get hungry quick (just like any baby), so you'll want to get some food for them as soon as you put the fry in the tank. The fry have poor vision and don't go far to hunt for food. You want to add enough rotifers in the tank so the fry don't have to swim more than 1 or 2 body lengths to run into a rotifer. That's a lot of rotifers!
You probably collected a few gallons of water while scooping up the fry. That is perfect. 5-10 gallons of water is fine in a 10 gallon fry tank. It doesn't really matter. Sometimes 5 is easier to keep rotifer density high for the fry. I like to use the broodstock tank water in the fry tank. They're fragile at an early stage, so making them go through a 100% water change isn't good for them.
So, lets get those fry eating. Make sure not to add rotifer water to the fry tank. The rotifer water is not good quality water. It can contain nitrates, ammonia, and other stuff. I try to culture my rotifers at a specific gravity of about 1.020. This is just higher than what I culture nannochloropsis at, and a bit under what the fry are at. Just siphon or scoop out a few gallons of rotifer water through a sieve and into a catching bucket. You'll notice you caught the rotifers in the sieve). Add the water in the catch bucket back to the rotifers.
So, add your rotifers. Wait a couple minutes and see how they have dispersed. Need to add more? Go for it. Get some more rotifers and add them to the fry tank. You'll want to be adding rotifers for the fry at least once a day (twice is better) for a week to 10 days.
Now that you have your rotifers in the fry tank, the fry should start eating. You'll notice the fry will get silver bellies when eating rotifers. So, the fry are eating. Here's the thing though. Rotifers are almost like brine shrimp to adult fish. They don't have a whole lot going on. You are actually wanting the fry to eat the phytoplankton. They get the phyto by eating the rotifers.
What happens to the rotifers after a couple hours without phyto? They don't have the same nutritional value. So, how do you solve this problem? Add some phyto to the fry water. Not a lot, you're not wanting the fry to swim through phyto, but you want to tint the water green. This way the rotifers will eat, and the fry will eat the rotifers. Brilliant! Remember how you have at least one airline tubing bubbling air in the water? This will keep the phyto up in the water column.
Adding phyto to the fry tank has other benefits as well. Baby fish have poor eyesight. Adding phyto to the tank is like adding a plain backdrop on a stage. It makes the rotifers stand out and easy to see. The phyto also helps to clear up the nitrates, phosphates and other stuff that is in the water. It helps to clean the water a bit. Having phyto in the tank also lets the rotifer population stay high. They have something to feed off of and make baby rotifers. This makes it so you don't have to add rotifers to the tank 30 times a day. Once or twice is usually enough.
So, you have set up the phyto, rotifers, and fry tank. You've got the fry eating rotifers for the first week or so. Excellent. You'll notice they grow somewhat quickly.
You'll lose at least a few fry every day probably. There is nothing you can do about it. Some of them just don't seem to eat well and die. Siphon the bottom of the tank every day with airline tubing. Obviously try not to get live fish in the siphon. Get the dead fish and poop out of there. I usually run this water through my rotifer sieve and add the water back to the tank.
Part 3, which will be the last part, should be posted tomorrow or Saturday.
Feel free to ask any questions (everyone, not just Kat).