5.5 gallon fauna stocking options (other than shrimp, snails, and bettas...have specific Nanos for those haha)? Thanks!
Forgot to add, fauna that would thrive in slightly harder water...
Mod: @charming-eelA lot of the stocking options for a 5.5g tank that aren’t bettas or the invertebrates you mentioned are going to be more finicky and require a higher experience level than some fish that are commonly recommended. That being said, here are a few stocking plans that could work:
Pygmy SunfishA trio would work best in a set up that small (1m:2f). If you kept more than one male in a setup that small they would likely kill each other. They typically require live or frozen food, a planted tank (or at least a tank with good cover and sight breakers), and low flow. A plus is they don’t really require a heater unless you keep your house exceptionally cool. There are some species native to my area and we have /very/ hard water and they obviously thrive here. You can do neat walsted setups with pygmy sunfish, as they’re really not as picky as some people say.
Least KillifishAnother native fish that can also work well in some brackish setups. I would do a m/f pair or a m/f/f trio. If you keep one of each sex you WILL get fry. Keep that in mind. You’ll either need to cull them or sell them unless you have more tanks to populate them with, and they’ll likely be eaten in any type of “community” tank. They do best on small live or frozen foods, in addition to plant matter or algaes. Planted tanks with low flow are pretty much a must have for this species.
CPOs (mexican dwarf crayfish)You did not mention no crayfish in your ask so I’m going to go ahead and recommend some. You MIGHT be able to get away with a m/f pair in a 5.5 gallon. My first set lived quite peacefully (with shrimp even) in a 5.5 gallon tank. With my second set however, the female had killed the male within a week. Sometimes you’ll get a good set, other times they need more space than a 5.5 gallon provides. VERY fun to keep, very easy and non demanding, like most crayfish. They can live in planted tanks quite well, although they will eat some plant matter.
Marmorkrebs (cloning crayfish/marbled crayfish)This would be a temporary resident for a 5.5 gallon tank. Just going to throw that out there. Marmorkrebs are super fun to keep, who doesn’t love an animal that clones itself and is peaceful enough to keep with other tankmates? I mention marmorkrebs because most people selling them are going to give you one in the 1-1.5″ range. A perfect size for a 5.5 gallon tank. They take around 5-8 months to mature IME, and I personally used 5.5 and 10 gallon tanks to grow out babies in. Because they can get around 5″ (though most of mine seemed to top out around 4″) you will need a larger tank to keep an adult or two in. Marmorkrebs are a great option if you have a larger carnivorous fish that will eat crays, so you have a way to keep your population in check, or if you want something to sell on the side. If you don’t have larger tanks available, don’t bother with them.
Most of the nano “schooling” fish (which IMO shouldn’t really be kept in 5.5 gallons anyway in most cases :V ) Will require soft, acidic water so I won’t mention them.
Personally, I don’t like nano tanks. I don’t really see the appeal. You’re always going to be super limited with stocking in general so if you don’t have the tank and supplies already... my main advice would be to get a bigger tank. I assumed you only wanted fw critters so I didn’t mention any of the obligate brackish or sw species that could work well in a 5.5g. If I had a 5.5g I’d probably fill it with some coral frags and a few inverts and call it a day.
