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|Corydoras are scavengers ???
|by Rob McLure
Corydoras metae - feeding on bloodworm
So let's start with a little story. Last fall, kind of on late notice, I traveled to Cleveland to take part in my first ever OCA extravaganza!. For those that don't know Ohio Cichlid Association is possibly the largest club in the state of Ohio and they focus almost exclusively on Cichlids and Catfish!
My primary reason for attending was to meet up with friends and swap fish, but I had a secondary objective given to me by former MAS president Rock Smith, to obtain a very appropriately acronymed "Dudes In Cichlid Keeping" T-shirt for him. One of the first talks was by my good friend, founder of Amazonas Magazine, Hans Evers. Given that this was more of a "general audience" talk (not for a bunch of Corydoras nerds), Hans really placed emphasis on the fact that "Corydoras are not scavengers" (said with a Hamburg accent, it sounds much cooler). I wholeheartedly agree, and I can tell you that while many shops may try to sell Corys by telling customers that they are good scavengers, or part of a "clean up crew" this advice is uneducated, and really not very good for the fish. If I could I would change this refrain to be "Corydoras are a fun and active addition to the lower strata of your community aquarium, and should be purchased in groups." More about that later, but for now on with this article!
If you would like to know what kind of feeder Corydoras are in nature, I would call them "Micro-predators". While some plecos, snails, shrimp, and other fish feed primarily off of whatever falls in the water, or even leftovers of what other fish have not finished eating - this is really not the Cory's MO. Being (probably overly) involved with this side of the hobby, I talk with a lot of scientists in the field, and I can tell you that gut analyses of wild Corydoras have revealed some pretty interesting findings (most notably ants and spiders), but the vast majority of what they eat are small aquatic crustaceans, insect larvae, and when they can find them aquatic worms!. I can also say that if you bought any fish besides a brackish water Scat to "eat the other fish's poo" You were sold a bag of goods! Other than the Scat, I have never seen any fish purposefully eat fish poo!.
One last thing to mention is that I currently keep over 40 Corydoras only aquaria, and I can tell you that each one of these has a "clean up crew" of sorts. I primarily use Ramshorn snails and Neocaridina shrimp - both of which do eat the left over food, and algae, and do a great job of it! So in summary, what does this all mean? I think for most people they tend to buy Corydoras for a community style aquarium. Over time their Corydoras don't do very well because they are either (a) feeding the rest of the fish which are top water feeders, and not much gets down to the places Corys can feast, or (b) finding foods that sink, but using the completely wrong diet - Algae wafers might be great for plecos, but while a starving Corydoras might eat them - their digestive systems are not made to handle all that plant matter.
I will cover some of the foods I feed my Corydoras in a later article, but for now just remember, if you want your Corys to thrive, they need sinking foods that are shrimp, insect, worm (or in a lack of all other possibilities) at least fish- based. While foods like beef-heart are way too high in protein for Corys (and really most other fish as well). They need animal protein in their diet! I will add one reply to this post below to share the funny part of my "Corydoras are not Scavengers!" OCA story. If you got to the bottom, thank you for reading my long winded ramblings! I'll try to keep most of them briefer!.
This article was first pulished for the Milwaukee Aquarium Society July 2020
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