Scenario - 2x 1-inch cories in 75 gal tank. Said cories hang out in one end of the tank within 1 foot of the end and seldom come forward unless feeding time. i.e. back corner.

Can I surmise that these two guys are getting a belly full in one place and have no motivation to take an excursion to the other end, so therefore I can add perhaps 4 more scavenge-mates to help scavenge the whole tank?

Hello garry...

Your Corys will be more comfortable if you have a minimum of five or six in a tank the size you have. I keep large, planted tanks of Corys too and stock about 1 for every five gallons of tank volume.

Corys can be different species, I've found they all get along very well together. I have four or five kinds in some of my tanks.

B

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Low Tech Water Building Keeper

Cories need to be in a group of at least 5. In a large tank like yours, 9 would be a good number. Your Cories are insecure and very frightened in such a large tank without buddies around. Add at least 7 more and you will see a big change in their behavior.

I didnt know this. I assumed they were solitary. Guess that explains why the one I have keeps hang'in out with the juvenile balas.. I'll be sure to get him a couple friends.

I have several cories in my tanks, at least four in each, and they are all over the place. In a 75 gal tank, I would have at least 6, and many more if possible.

I guess ir is off to the LFS for me! I want enough to do a great scavenge job and have enough to eat but not so many that I have to feed them specifically. Amybe I will add 6 more then.

Also I want to add a few other fish. increase 4 mollies to 8 because they constantly scour the plants for food particles/algae.

And a pair of Paradise and a dozen of Bolivian Rams.

current stock:
4 molly
2 cory
1 gouramie
1 betta
2 shark
4 neon tetra
6 black skirt tetra
5 tiger barbs

In my 33g I had 5 albinos and 2 sterbais and they all stayed in a fairly close group and tirelessly scavenged all day, everyday. Although after a tank incident I lost all my albinos and currently only have the sterbais left and they have definitely tamed down a lot, stay mainly in the tank ends and only come out long enough to shoot too the other end and you can tell they aren't as comfortable in the tank. With that being said I am currently scanning over my whole area within reasonable driving distance to find sterbais but it's next to impossible to find them so I'll probably have to settle for the Panda or Salt and Pepper variety and hope my new corries get along with my other two as well the albinos did!

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30 Gal breeder: 2 Honey Gouramis, 3 Sterbai Corries, 8 Black-Skirt Tetras, 1 Albino Bristlenose Pleco, 1 Common Pleco (temporary home) and 2 Nerite Snails
10 Gal SW - Still cycling

As far as feeding goes, I bought some shrimp pellets and drop one in every couple days just to give them something different to nibble on and they love them. When I had my group of them they would fight over the pellet so I'd have to drop another in to even out the fight a bit, they also flock to the algae wafer I drop in for my Bristlenose once in a while but the pleco usually puts the run to them!

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30 Gal breeder: 2 Honey Gouramis, 3 Sterbai Corries, 8 Black-Skirt Tetras, 1 Albino Bristlenose Pleco, 1 Common Pleco (temporary home) and 2 Nerite Snails
10 Gal SW - Still cycling

I have 3 albino and one pepper in my 29gal and they cover the whole tank which is heavily planted. I give them algae wafers once a day. This is the first time I have had long term success with corys. Probably because I have a group of 4. They do need others of their own.