My two favorites are Caridina japonica and Ancistrus sp. In the tank with cichlids (shrimp unfriendly tanks), I have one Ancistrus sp. per 30-40 gallon. In non-cichlid tanks (usually smaller tanks), I use Caridina japonica at 1-2 per gallon. There are other shrimps (Neocaridina sp., Atyopsis sp., etc.) and ottos (zebra, red, etc.) but they are for my viewing pleasure and not algae-control. I would never employ C. japonica in large tanks because the # required would put me in the poor house. It's not like I can order 50 or more shrimps to use for a couple of weeks and return the excess at a later date. So practicality also comes into play.
Aside from these two, I don't find the need for any other species for 'cleaning' purposes.
I've always kept otos in my tanks. I keep 2-3 per 10 gallons. Also have one ancistrus species and I love that little guy in my 20. Watch him on the glass and just pick it clean. Small SAEs are decent also until they get the taste of flake food, then they are worthless to me. Fun to watch but not what I want them for.
And cories are great for pickup left over food on the bottom between the regular feedings.
Shrimp are great, but they limit what you can put in the tank in terms of fish. I love dwarf cichlids in my planted tanks as it provides an ideal breeding setup for them but the majority of these guys will make a meal out of most shrimp. As far as bottom feeders go, I prefer small loaches over cories as they are more suitable to maneuver through thick plant growth. Botia sidthimunki and Khuli loaches are great. As far as algae eaters go, I have found that Sturiomaticthys leightoni, the dwarf Royal Farlowella is hands down the best. I know no other fish that can clean BBA off of an extremely infested Crinum calimistratum without cracking the leaf.This fish will chew on cyanobacteria too! On top of all of this, it is really pretty and easy to breed. This is one fish I think I will always keep.
The 3 in my 55 Gal are the biggest, at about 3 1/2 inches, and they do chase each other around a little kida' like Zebra Danios do.
But there is lots of room and hiding places for them.
All the ones in my other tanks are about 2 inches and are alone species wise and don't bother any of their tank mates, as a matter of fact they all seem to hang around with the corie cats a lot for company.
Big rainbows won't hunt down shrimp like cichlids do so they are usually okay. Shrimp are pretty good at staying out of the way of larger fish. However, if a shrimp gets startled and swims into thewater column, it is probably history. When I had my 125gal setup with rainbows, I had hundreds of shrimp in it (a local variety found in streams) and although the rainbows would take out a few now and then, the shrimp population was never in jeopardy.
Farlowellas are pretty tough however they do not ship well. I'd say if they have been in the store for a while, then go for it. I can't speak on all the other species of twig cats out there but S. leightoni is super easy to breed. I don't even condition them and they produce viable eggs. In fact, the young of my original fish are breeding too. The one thing is that the fry are very difficult to raise.
First, CAE's are a big mistake in a planted tank! I once had two that killed a pair of Angelfish and a pair of D.Gourami(I ended up giving them to my friend to feed to his Piranha) They may eat algae when young, but as they grow older they begin to get a taste for the fish's mucus membrane(basically they're a parasite).
Secondly, I have a few favorites:
1. Otos/Oto sp. 'Zebra'
2. SAEs (Great for black beard algae)
3. Farlowella acus (Great for algae on glass)
4. Cherry Shrimp
LOL, if that is the case, ask the new guy to catsh them out and tell him they are worth 1.99! Just kidding, Farlowella sp. goe for about 6-10 bucks over here. My Sturiomaticthys retailed at $25 each but got them half price... I used to work there and they give me employee discounts when they are feeling generous!!! Sturiosoma sp. can go for as much as 40 to 50 bucks. My fish are reaching the end of their breeding season (Oct.- May) At this time, the males grow "beards" called odontodes. (I think) at this time they are easy to sex, after this, the beard falls off and they look the same to me.