atmmachine816
Fish Gatherer
same thing just wondering if they owuld be compatible in my tank
edit-Albino Or Just Bristle Nose Pleco
I would say, sort out the fish you have first, before thinking about new species.
I'm particularly concerned about the lone tiger barb stuck with a single cory in a 2.5 gallon. Is there any particular reason for this arrangement? Both tiger barbs and corys are schooling fish and need to have their needs met.
On the other hand, it's going to be tricky to house a school of tiger barbs (or indeed any tiger barb) in a main tank containing fancy male guppies and a betta.
If I were you I would rehome the tiger barb. See if the shop will take it, or if you can find some other hobbyist who already has a school. Move the betta into the 2.5 gallon, it is the only fish that tank is fit for. Move the lone cory into the main tank, and up the number of corys to 5 (of the same kind). This will pretty well fill your available bottom space, if your dwarf suckermouth is any kind of pleco or bristlenose (ancistrus).
If it is an otto, it would be happier with others of its kind, get 2 more.