Restocking With Elderly Fish

Hey y'all! I've had a 55 gallon hexagonal tank for years, and it was initially stocked with tiger barbs, rosy barbs, and lemon tetras (the lemon tetras weren't planned, I took them in an emergency with a neighbor's tank and they ended up being fine with the barbs).

I left for drum corps over the summer and college, and now I am home. My fish were all around 6 years old when I left and had been dwindling in numbers, and my sister who took care of the tank did not restock while I was gone. I am now down to 1 tiger barb, 1 rosy barb, and 1 lemon tetra. I feel so bad to have them living without a proper school, especially the rosy barb which is showing physical signs of stress, but they're also quite old and I'm worried that they're big enough to bully anything young and small that I put in (especially the large-ish lone tiger barb in the tank). I'd like to restock eventually, preferably with something other than barbs. Right now though, I don't quite know what to do in the best interest for the 3 fish. Should I get over it and just restock with barbs, leave the tank alone for now and let them die of old age, or some other option?

(side note: my sister is well-instructed on how to care for the tank in my absence, so I am not concerned about difficulty. In retrospect, I should have asked her to restock before it got to this point, but you live and you learn)

 

EDIT: By "leave the tank alone for now and let them die of old age", I mean take care of them like always and just wait to restock until I've got an empty tank, NOT to just let them die of neglect or anything. That may have been obvious, but just in case it wasn't.

 

I don't know the answer to you question - I think it is a really good question, so If you don't mind I am going to tag along and see what responses you get from the more experienced members.

 

I don't know the answer to you question - I think it is a really good question, so If you don't mind I am going to tag along and see what reponses you get from the more experienced members.

 

I would restock, do around 10 of each species, that way the old fish at least can pass their knowledge to the young folk. It would also make the older fish less stressed to be in a proper school.