For those concerned about feeding a mandarin, you might consider culturing copepods. It's pretty easy, and with the availability of concentrated phytoplankton preparations from Reed Mariculture, you only need to set up the pod tank and don't have to mess with culturing phyto (though I do it because it's easy). Here's a post from another thread where I outlined the requirements - it's simple, extraordinarily inexpensive, and highly effective at generating massive amounts of copepods. The only ingredient I'd steer someone away from is Algagen's Phycopure - it's not very concentrated, and is pretty expensive at about $20 for a 16 oz. bottle, which you'll go through very quickly in a pod culture:
If you already have the dragonet, you may want to consider immediately setting up a copepod culture outside of your tank. The amount of copepods you need to generate to keep a dragonet healthy is quite large, and is somewhat difficult to do even with a large tank (120 g or larger) and/or a large refugium of >20 gal.
But culturing copepods to a high density is pretty easy in a separate culture vessel. You need the following to culture them:
1) Culture vessel. I use some Lustar plastic 2.5 gallon tanks leftover from my killifish keeping days, but you can use virtually anything that has an open top, including a partially filled 5 gallon bucket.
2) Air pump. Any air pump will do, and you will also need a piece of stiff plastic tubing that you can weight down on one end by tying on a piece of rock with a plastic bread tie. While you can use a standard airstone, that's not preferred because it will quickly clog in the culture environment - a simple open-ended tube that emits large bubbles is what you want.
3) Food source. For most copepods commonly available, this is phytoplankton. You can culture phytoplankton yourself in a a separate culture vessel using nothing more than miracle grow plant food. Or you can buy concentrated phytoplankton from Reed Mariculture (Reef Nutrition's PhytoFeast is one of their concentrated phytoplankton products, but they have others). One simply puts a few drops of phytoplankton into the copepod water sufficient to make it slightly cloudy.
4) (Optional) Light source - copepods don't need light to grow and reproduce, but if you're using live phytoplankton like I am, having a light source over the copepod tank lets the phyto reproduce in the tank until it's eaten.
5) Filter for copepods. You will not want to put the copepod culture water directly in your tank. Instead, get a piece of Nitex cloth in the 35 um opening size. Nitex is sold by a number of sources in a large variety of opening sizes specifically for the purpose of filtering various sizes of plankton from seawater.
6) Copepod starter culture. You can get this a lot of places, but if you want pure single-species cultures, I'd suggest AlgaGen's copepods.
