Gravel And Spotted Cory


I have a few questions. Any help would be appreciated. I have a 36 gal. freshwater tropical corner unit tank that has been establlished for about 2 years. I think I have too much gravel on the bottom of the tank. I only have a top bio filter. I think I misread the instructions when I first set up the tank. I put the amount of gravel the book suggested for an undergravel filter. I have about 2-3 inches of gravel. I have a community tank and will go for long periods of time without losing any fish, then I start losing about 1-2 every other week. I perform regular monthly gravel vaccuumming and weekly water change. Can I remove the gravel that is in there and leave about a 1/4 inch without tearing down the whole tank? I it possible that even though the tests come out normal at pet stores and the water is clear that I am unable to really get the gravel clean? Also, I have had 3 black spotted cories since I have had the tank. Just today I noticed that one of them has a red "hole" behind one of its gills. It has been swimming all over the tank, which is completely out of character for it. I read one website that referred to this as "red spot" disease specific to cories and it said it is highly contagious to the other cories, but not any of the other fish. The article referred to the "plate" of the catfish. Is a plate close to the gill or is it another name for the gill?
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Did you write down the info on your water parameters they gave you from the pet store? You should be checking for ammonia, nitrite, nitrate and pH. What temperature do you keep the tank? If you can provide your specific water parameters we can look more closely at what's going on in your tank.

Cory cats have plates instead of scales. They are nicknamed "armored" fish because of these plates.

Do you have a quarantine tank that you could transfer your cories to? You could then treat them for the "red spot" problem. Sounds like it may be a bacterial infection. Research any medicine you plan to use and make sure you can use it on your cories because some medicines can kill them.


I also think I have 2much gravel in my aquarium (63 litre-16gallons) I took sum of mine out with my net I just scooped sum of it up it made the water pretty cloudy but the filter soon cleared it but I would not recommend doin this lol although my fish survived well, it scared the **** out of me and I was stupid doin it!!!!! the gravel does contain sum important bacteria for ur fish but its a tough 1 my gravel height ranges from about 2 inches to about possibly 3 or 4 in the middle but it all slopes forward its just not flat the gravel around the edges of my tank is filled to the mark around the edges but my dad looked after aquariums in college when he was a young lad lol and he told me 2 put sum more in and I did then I read u aren't meant 2 hav so much so that's when I took sum out!!


I have read that 1/4" of gravel is enough. I actually have a mix of gravel & large rocks (stones). I have 2 small corys and I had a larger spotted cory who just recently passed away (for unknown reasons) but the other 2 are fine ??? I don't have an undergravel filter, just a power filter on top. The spotted cory seemed fine-and then gone Good luck with yours. Hope they're not sick.

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