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Still on the fence about adding a small group of "earth eaters" to my 55-gallon South American tank. I've got a few schools of Tetras, a school of Corys, and an Electric Blue Acara lined up. Considering a trio of juvenile Red Head Tapajos, but I'm worried about how they'll get along with the Corys. I also don't want to be raking the substrate daily, especially with three of them. I do have an under-gravel filter, though. My substrate of choice is this stuff from Amazon - I've used it in two tanks so far and I'm happy with it. The tank will have a mix of house plants rooted in the tank, silk plants, driftwood, Maramo algae balls, and some Red Root Floaters. Nothing too traditional or that a Geophagus would destroy. Most of the fish will be small, except for the Corys, which are already over an inch.

When it comes to South American cichlids, I've learned it's generally better to stick with just one species of bottom dweller per tank, unless you're working with a massive tank - we're talking way bigger than my 55 gallon.

I've read that they supposedly coexist with Cory's just fine, the Cory's will just vacate the area & the Geo's won't bother 'em.

I've got a resin stump/cave in the tank, medium size, and I've noticed all 6 of the Cory's have been using it at "lights out" - kinda surprised they all fit & seem to like the same spot. water's cleared up a lot now, so I'm gonna start on the aquascaping.

Considering your setup, I'd advise against the Geophagus this time. As earth eaters, they're all about shifting sand and passing it through their gills to find food. With gravel as your substrate, they won't be able to do that, so it might not be the best fit.

Considering a Biotodoma species over Geophagus might be a better fit for your tank. Since the tank size is just about the minimum for Geos, it could be perfect for a school of 6 or more Cupid type Cichlids.

I came across Biotodoma Wavrini in the wild, but I've seen them in a display tank before and they're truly stunning. The species they get their name from is Biotodoma Cupido.

A group of 6 of these with one Electric Blue Acara could work well together. However, with either of these fish, you might want to reconsider your substrate. Gravel isn't suitable for them, as it poses a significant risk. You'll need a very fine sand, as they push it through their gills. Anything larger will get stuck and cause damage, potentially leading to wounds and infections. If you haven't set up the tank yet, consider changing the substrate or choosing different fish. It's a simple change that'll make your life with these fish much easier.

Considering the earth-eating habits of Geophagus, I'd advise against them with a gravel substrate. They won't be able to sift through it like they would with sand, which is a crucial part of their foraging behavior.

I'd say this is basically sand, just a bit coarser. To me, it's the closest thing to sand I've ever used in a tank. The Cory's seem to be handling it just fine, no complaints there. I've had this under gravel filter system for ages, it's one of the best on the market, and I'm not about to get rid of it now. The thing is, if I switch to super fine sand, it'll just clog up the plates and cause more problems than it's worth.

bettaMagenta wrote: ↑Fri Dec 20, 2024 4:41 pm Still on the fence about adding a small group of "earth eaters" to my 55-gallon South American tank. I've got a few schools of Tetras, a school of Corys, and an Electric Blue Acara lined up. Considering a trio of juvenile Red Head Tapajos, but I'm worried about how they'll get along with the Corys. I also don't want to be raking the substrate daily, especially with three of them. I do have an under-gravel filter, though. My substrate of choice is this stuff from Amazon - I've used it in two tanks so far and I'm happy with it. The tank will have a mix of house plants rooted in the tank, silk plants, driftwood, Maramo algae balls, and some Red Root Floaters. Nothing too traditional or that a Geophagus would destroy. Most of the fish will be small, except for the Corys, which are already over an inch.

Going by the photo, I'd say that's definitely not sand. And as for the undergravel plates, sand will indeed pass through them, which seems to settle the issue.

From the link I posted, that "gravel" I'm using is actually 2mm to 4mm river-rounded granules. I've used finer substrates before, but this one's still the finest "gravel" I've ever worked with. I'm curious, did anyone actually look up a definition of sand, or was that just a passing comment? I'm not looking to create a muddy mess in my tank, so I'm not about to switch to something super fine that'll just lead to bacteria pockets. Guess I'll just have to trust my own instincts on this one. It's a shame that a genuine question can go unanswered around here, but I suppose that's just the way it goes sometimes.