Feeder Fish???

Question
I have a 5 gallon tank and one feeder fish (My goldfish recently died). My tank has a new Tetra Whisper Filter. I use a pH balancer, ammonia neutralizer, algae destroyer (Not that often),and Freshwater salt (with every water change). I feed my fish sinking pellets, two different kinds of goldfish foods, baby shrimp and usually some spinach. Usually I feed her spinach in the morning and half a flake of goldfish food long with  little bit of babyshrimp at night.And the sinking pellets are a treat, that she actually takes right off my finger. I've had this feeder fish for 9 months and it's two inches. I was wondering if It's grow any more? Also, could I add another feeder fish to my tank, without over crowding it. And if not, is there any other fish I could add that would get along with my feeder fish, and wouldn't overcrowd my tank? Thanks(: Please hurry I want to head to the pet store tomorrow.

Answer
Your feeder fish probably won't grow much larger, Miranda, but I have a comment about the chemicals you're bathing him with. I know you mean well, but please stop spending money on them and using them.

PH is not necessary for a feeder fish's tank.  Don't use it.  Instead, sink a piece of driftwood or some peatmoss inside a net and submerse it in the filter.

Stop using the algae destroyer.  A clean tank has no algae.  If you get algae, change water more often.  You are supposed to siphon out 25%, at least once a month.

Salt isn't necessary for him.

Your foods sound fantastic.  Good choices! :)

You might get one more feeder fish to befriend it. :)

Happy fish-keeping.