Optimum Number Of Corys

[daveg6529]

I have a 260ltr fresh water tank. It has been up and running for 8 months and is cycling well.
It is stocked with
6 Neon tetras
7 Penguin Tetras
10 Glowlight Tetras
10 Harlequin Rasboros
2 Glass Catfish
6 Corys
PH is 7.5, Amonia is 0,25, Nitrite 0.5, Nitrate 20 and the temp is 24c 
 
My question is how many more Corys would be needed to keep the tank cleaner?
How many could the tank cope with?
I have white gravel and its turning brown.
Any help or advice would be appreciated.

 

[blackops]

corys prefer sand

 

[Lilfishy]

Corys will not clean the tank, they will clean up any food that drops to the bottom but you do need to feed them their own food.
They do best on sand but if your gravel isn't sharp they'll be fine
White gravel does have a tendency to go brown or greenish, nothing much you can do about that, just do extra gravel vacs to prevent any build up of detritus

 

[blackops]

your ammonia is to high

 

[Lunar Jetman]

I'd be more worried about those nitrite and ammonia levels if I were you. Are you saying you've been cycling for 8 months? And with that volume of fish?

 

[eaglesaquarium]

Minimum number of corys of a specific species is 6.  Optimum number of corys would be somewhere between 100-500 individuals.
 
 
As to the specific questions about "cleaning"...  Cleaning is the job of the aquarist, not the fish.  Corys are bottom feeders, not a cleanup crew.  They need to be fed specific food that is designed for them, not just the scraps from the top feeders.  Snails, shrimp, etc. are good for cleaning up extra food, that's not the role of corys.
 
 
And, I'd never add any new fish until my ammonia and nitrite levels are both at a CONSTANT ZERO.