Your water is too soft for shrimp unfortunately, except maybe some of the caridina shrimps, so don't suggest those. And also too soft for snails. The caridina shrimp like softer water and are pretty, but would be an expensive snack potentially. Adults would be left alone but babies would be chomped.
Great water parameters though for some otocinclus, but id swap to live plants before adding those. How long has the tank been set up? Would suggest them only if the tank has been set up for 6 months at least. But even so, they may not eat harder algaes. They will love diatoms though. But if you opt for them, they may require supplements still of wafers and veggies, if you can convince them to eat them.
But thats only if you want more fish. They need groups of 6 at least as well. If you choose them, check that they don't have sunken in bellies when you buy them. Theyre a bit delicate.
But, on the other hand, you would have more gravel vacuuming and filter cleaning to do with adding more fish as well, so think on that one. Wiping down the glass and keeping a good eye on your light timing and intensity may be easier.
So just depends if you want more fish or just looking for something to ease maintenance. If you want more fish then yes. Want easier maintenance, better to stick to just wiping it down yourself.
