if you want plecos you may well wanna try rubber lip plecos which only get about 5 inches.
others include the regular Common Pleco
averaging in at about two feet.
and the albino chocolate pleco at about 18 inches.
for my part, i dont typically recommend plecos. they get big...and so ive heard as they get bigger they get lazier. also, they will feed on things more important to their taste buds then algae. like if you have driftwood in your tank or food on the bottom from other fish.
im not sure how these work with the aggression levels of your fishes but otocinclus are amazing algae eaters, even though they only get 1.5 inches or so. they actually prefer feeding on algae most of the time and will even feed on plant leaves.
if i had the tank setup id also love to stick a peacock eel in there. they get about a foot and are beautifully colored. They bury in the gravel which mixes it up and kinda pushes debris out to get sucked up by the filtration which is a nice addition to clean up crew.