for stock im thinking for fish (6 options)
a pair of red spot glass cardinals - if Liveaquaria had to feed these guys a whopping 10x a day at first, not sure
pair of copper cardinals - they prefer larger groups
pair of gumdrop coral crunchers - interesting fish but you may not see them and a pair may be too messy
pair of yellow gobies - gotta get a mated pair or they'll fight, need a lid
1 neon goby - always a safe choice, tbh, needs a lid. Mated Pairs are readily available
1 possum wrasse - needs a lid, maybe too big
1 brachiosaurus blenny - I've never seen this one before, learn something new everyday.
for inverts:
pair of harlequin shrimp - they only eat starfish, you ready to always provide? Otherwise they are very cool
fire shrimp pair - gotta get a mated pair... may be too big for a 5g
pom pom crabs? - gotta get a mated pair or two females, males will fight. I've got a male
maybe a lettuce slug? - nah, but you already came to that conclusion on your own
ive aslo got an aquaclear 50 thats not used and if its silent enough im thinking setting it on low flow and adding rubble rock or something to it - NO! Make it a refugium! I will show you how, it's awesome to do.
im also going to add plants too, tufted joint weed, gracilia, stuff like that. - ask me about the plants,I can tell you where to go.
i found a forum with a LA rep and they said that they were pretty easy its just that at first they are kind of hard to take care of
noooooooo so cool fish *sigh* maybe for the 90 if they don't fight with my couple (ive got eggs! daddy ate them though)
coral crunchers- LA lol or maybe my lfs can special order (im consulting them as well because they seem pretty reasonable, and then i cross examine both advice and pick from whatevers left)
yeah gobies need pairs, even the little guys lol, i was also thinking court jesters?
lol neon gobies
ive heard possum wrasses are ok for 10 gallons so idk i thought maybe by itself it might be ok, considering they dont get too big (>3")
the blenny gets 3" long, too big?
yeah im ready for the harlequins, my rock has lots of brittle stars and im going to try to get a bunch of asternias and stock up on them, as well as maybe buy a chocolate chip star and use it for food (though im still thinking about the star since i literally am cutting it in half

i was expecting for fireshrimp, or any shrimp, to need a pair/ big enough tank (btw my peppermints spawned again)
i have never seen a pom pom IRL so im assuming if LA gets a pair/ willing to send me one or just get one if i ever see it.
and you know im going to be asking questions with the plants lol