FWIW....I noticed you have a 90 gallon tank. Do you have plenty of live rock, and is your substrate appropriate (at lest a couple inches deep)? Or are you going bare-bottom? If you have a 90 gallon tank, live rock and sand, you aren't going to need to 'raise' copepods or amphipods...they will do that themselves. Especially since you noted that you were waiting a 'couple months' to add the mandarin. GOOD FOR YOU!!!! Most people lose them because they add them way too early, and the population of foods is not yet established (this by the way is assuming you don't have a bunch of other copepod predators already).
If, however, you want to raise more in your filter and have the space to put in a bit of rubble rock....then YES they will breed in there. Here's a great trick to feed pods to your fish that people don't want you to know about:
Most pods LOVE PVC tubing! HA! It's true. Raised them for years and years by simply placing 2-4 inch pieces of PVC tubing in dark areas such as the sump around rubble rock. I use 1/2" PVC for this. When I want to feed them to the fish I simple pick up a piece with my fingers over the ends, cary it up to my tank and use a bottle brush to brush hudreds and hudreds into the tank from the inside of just a few pieces of old 1/2" PVC pipe. Of course, my mandarins have never ever gotten any of this because they 'prey' and 'hunt' amongst the rock rather than trying to catch free swimming pods. My other fish, however, like it a lot.
Hope that helps. God bless......
