I'd have to agree. I caught a 9in bass, and he was over 11 in when i released him a few months later in my friend's pond. If you get them smaller they will grow at an even quicker rate if housed and fed properly.
A 30g is also pretty small for a redbreast.
Consider choosing from darters, sculpin, madtoms, some of the smaller sunfish (blackbanded, banded, redspotted, bluespotted, orangespotted, bantam), pygmy sunfish (not true sunfish, need live food, otherwise hardy) various dace/shiners, or killifish/topminnow.
Avoid anything called bass, it will outgrow your aquarium.
Common sunfish like bluegill, green sunfish, warmouth, redbreast, redear, pumpkinseed - should have a 40g breeder or larger.
Catfish other than madtoms grow far too large.
"Minnows" need to be properly identified, because some, such as "chubs" and carp, may resemble species of smaller minnows as juvies, but may grow to 12+ in.
Depending on your fishing regs, or what is available in your area you may be better off ordering online for small species. There are several native vendors, such as
http://www.jonahsaquarium.com/, and they also come up periodically on aquabid.
Some, like flagfish or other killifish are found in regular fish stores quite often, and feeder fish such as rosy reds are just a color morph of the native fathead minnow.
ill release them where i caught them, they already have an establishd population of 8-12''+ largemouths there
Don't release, unless into a private impoundment, unattached to any other water source.
It's bad form, can spread disease, not to mention illegal in many areas. Only release into private ponds, or humanely euthanize.