Two books I highly recommend are:

Fish Disease: Diagnosis and Treatment by Dr. Edward J Noga.

Captive Seawater Fishes: Science and Technology by Dr. Stephen Spotte

While not the easiest reading, they are both superb.

Both books are somewhat expensive but are well worth the money.

Yes and no. Depends.
A fish-only may benefit from a filter in the system, but!
Here's a list of useful facts to consider.
1. ONLY live rock and sand can break somewhat-harmful nitrate all the way down to harmless nitrogen gas. Bioballs can't and a filter can't. They take waste down as far as nitrate and stall there. Nitrate builds up and up until there's a cleaning-out of same.
2. Fish can tolerate higher nitrate than corals can. They'd probably rather not tolerate it,...

Nice tank man! The more I see the Kessil's, the more I want one.

I have always used chaeto in...

Nice tank man! The more I see the Kessil's, the more I want one.

I have always used chaeto in...

Run it. Now. To see where you are.
If ever things are going squirrel-ey---test your alk.

...Then test it weekly, during your first half year. Bi-weekly thereafter. This is for fish-onlies AND for reefs both softie and stony. For all tanks. Alkalinity is THE most important test for a reef, once you pass your cycling hurdle. And for a fish-only, alk controls so very much regarding fish health, just consider it an absolute essential. If it's right, you've got a major part of fish-care...