What are good dither fish for corydoras and plecos?

[Yanni]

I want to try and breed some corys but I want to also have other smaller fish at the top and middle layers of the tank. I was thinking some rainbow tetras, diamond tetras, lemon tetras, or black phantom tetras. But what are some good dither fish for corys or plecos? Will guppies handle the lower ph's? Will those tetras above even work?

[Scapexghost]

I would do a type of tetra. The smaller the better, since they'll be less likely to prey on fry, so I would do neon tetras just bc theyre the cheapest and most widely available, but you can basically do any type of tetra you want outside of vampire and exodon tetras. Some tetras would be better than others. Smaller and less active tetras will be better than larger or more active tetras.

[gardenman]

There are semi-pro pleco breeders who keep guppies in their tanks as they believe the hormones secreted in the copulation/birth processes encourage their plecos to spawn. Are they right? Maybe. There is some logic to it. The guppies are small enough to not unduly prey on the pleco fry.

[GameCzar]

How big is the tank?

 

[Guppysnail]

Guppies prefer higher ph and need high gh and adult female guppies will eat both types of fry. I keep guppies pleco and Cory all in one tank and they do fabulous but I am at 7.6 ph. I do keep celestial pearl danios with BN pleco panda and Pygmy cory. It works terrific but they will eat Pygmy fry.  Tetras I think would do fine though I’ve not kept that combination but would also consume Cory fry. 

[anewbie]

tetra are a bad choice since they will go after the frys/eggs; pencil fish might work.Also the bottom needs to be well layered because cory will eat their own fry - pleco will protect their frys.

[Beardedbillygoat1975]

First if you want a high yield of corys or plecos you’ll want to have them on their own or some will breed them together I think Malik keeps them together in some of his setups. Most of us don’t want a strictly breeding setup so we have to make some compromises.My colony of BN plecos are in my community tank. However, the group I'm getting from Greg Sage will be in their own setup.  
Endlers don’t care what the pH is (sure they prefer it middle of the road but they’re just that hardy) and I’ve seen a few German breeders using them with their ancistrus and hypancistrus colonies with reports that the hormones in the water encouraged the plecos to breed. 
Agree with @anewbieabout the corys they aren’t at all protective of their eggs. Figuring out the timing and locations they’ll lay in will be super important. Loved Eric Bodrock’s coop videos for hints on usual preferred breeding locations for various corys. My aneaus like Amazon sword leaves and the glass adjacent which happens to be right under the outflows of my spray bar from my canister filter. 
Plecos as cave spawners really no concerns about tank mates. They will protect the hell out of their spawn unless they fungus up and aren’t any good. Then they’ll kick out the eggs or abandon them or sometimes they’re just bad dads. Dead beat pleco dads I guess. 

Big Daddy here recently abandoned his cave when that big clump in the upper left corner completely funguses up leaving about 13 wrigglers that I was able to scoop up. 

Have fun and look forward to hearing more about what you decide to do! 

[gardenman]

I've found that when pleco eggs get kicked out, it's usually a competing female who kicks them out. I've seen it a couple of times in my fifty. One female will lay her eggs then swim off and leave them to the male to tend to. Female two will then swim in sometime later, push past the male, knock out the other eggs and lay her eggs there. When I find the eggs knocked out, I typically move them to a breeder box and let them hatch. If you ever find eggs knocked out of the cave, it's probably the work of a jealous female. Good males are apparently hard to find in the pleco world and the girls will resort to whatever it takes to get them to watch their eggs. 

[Andy's Fish Den]

I know of a couple people who keep and breed corydoras and plecos, use rainbow fish as dithers and also breed the rainbows in the tanks as well.