Cory Melanistius Freaking Out

[madmonkey04]

I have a 100L tank planted with 2 pieces of drift wood and 3 hollowed out coconuts. I have 6 Guppies 4 Glowlight tetras, 4 Red eye Tetras and 3 Corydoras Melanistius.
Every time I go to look at my tank or feed my fish I allways see the Cory's hiding and when I clean it they freak out a bit understandably. But when I just go to look if they are not hiding they will see me and then freak out and swim really fast against the tank's glass as if they want to get out, they then eventually find their little cave and stay their. Now I know they are mainly most active at night but they are not as active during the day as they were when I got them. I have had them for 1 year now. They are healthy and well nourished from what I can see but they are just acting very weirdly. Can someone help me understand what is going on. Or tell me if this is natural behavior and if it inst what I should do to help them. My tank is clean I do a water cycle once every week and a half, There is minimal algae and two air stones.

 

[Akasha72]

Hi, cories are natural shoaling fish and so need to be kept in larger numbers than 3. I would advise doubling their number to 6 - you have the space to accommodate 3 more - BUT - you need to get 3 more Melanistus as they need to be kept in group of the same kind. 
 
Cories also like to have hiding places and shade. Is your tank planted? You mention you have some wood and coconuts and that is good as they will use these to hide in when resting but I'd also advise providing shade from plants too. My cories are generally to be found hiding under wood or resting in the shade of plants. They don't like my bright lights or me crashing about in their home and mine do the same as yours if there is loud noise in my home or I approach the tank too fast. Cories can be fairly shy if they feel exposed and that is possibly what is happening with yours.
 
I would also look to up your tetra number if you can. Again, they are a shoaling species and need to be kept in double the number that you have as a minimum. The problem you may have there though is space - or rather the lack of it. 
 
I hope that is helpful

 

[Byron]

I would get more of them to start; a group of six would be much better.  This will not impact your aquarium's biology very much, and actually having more of the corys will make things better as they will be less stressed and thus impact things less.
 
My second observation is that this is very common with many fish, especially corys, if they are in a fairly quiet location for the majority of the day.  In more active areas where they get used to people around the tank, they often become less frightened of someone approaching the tank.  The normal cory response to perceived danger is to remain absolutely motionless, and then rapidly swim away if they still feel endangered.  Mine do this all the time, as my tanks are in a dedicated fish room which is very quiet except when I'm present.
 
Byron.
 
Edit.  Akasha posted as I was typing...we are on the same page.  B.

 

[madmonkey04]

Thanks that helps a lot I will be sure to get more Cory's and I can move all my guppies to my other tank which should help. My other tank is a 40l tank with 2 Golden Balloon rams.

 

[Akasha72]

the rams technicly would be better with the cories and tetra's. All these fish are soft water loving fish and so keeping them together is more natural. The guppies are on the opposite scale - they are hard water loving fish