Cory Behaviour And Soem Losses

[Marve99]

Morning all

I have a 200 Litre planted aqauarium with the following fish

1 angelfish
12 Black neon tetra
9 Rosy tetra
2 BN plec
5 Sterbai Cory
4 bandit Cory

About 6 weekd ago, 1 of the Sterbai started behaving strangely. Allowing itself to float at odd angles in the current, darting around at incredible speed doing somersaults and crashing into objects, and then acting normally for a couple of days, then odd again for a few hours. I have thought him to be close to dead on several occasions, only to see him swimming around with the other corys and eating the following day. Then 5 days ago, I spotted a bandit cory playing dead, lying near the surface in one of the plants. I watched him for a few minutes and he eventually started swimming around again. I have been ill for the last 5 days and have not been observing my fish, but today I seem to be missing 2 bandits, I have watched for hours and nothing, so can only assume they have died - but tank is far too densly planted to find any bodies.
Edit - Tonight one has reappeared, so assume only the one which had been looking under the weather has died.

The last water change was 6 days ago - 30%, but when I tested water this morning, I can see that tank PH is up to 7.4 ( normally 7.0), so tested tap water which is always at a steady 7.0, and this in the region of 7.6!, could an instant swing from 7.0 to 7.6 following my water change have effected my bandits? All other water params are good (Ammonia and nitrite=0, nitrate less than 5, KH - 3, GH-5, temp-26)

Has anyone had similar experience of strange behaviours in sterbai cory?

One other thing is that the tank is fairly tall - around 50cm,although there is plenty wood far nearer the surface which they do spend alot of time on - could this stress the bandits?

Appreciate any advice

Thanks

Paul

 

[Marve99]

Any cory behaviour experts have any advice?

 

[Fintastic!]

I'm sorry I have no advice Marve, but I have an Albino cory who acts like this overy now and then. Boy they can move fast when they want to. I asked advice here some time ago and someone said it was some sort of spawning activity. I hope someone gets back to you on it as I'd be interested to find out more. My fella has been like this again only these past few days, darting up and down the walls of the tank and hitting into things but seems strangley fine during all of this.

 

[Tizer]

corys do tend to go bananas from time to time, i wouldnt worry too much.

 

[Marve99]

Thanks - I have lost a bandit cory today, can not be sure if its the one which went bananas, but he did have some barble damage and looked quite sore around his mouth. Substrate is Aquasoil amazonia and a mix of sand, with some large smooth stones and lots of wood, so supised he has damaged himself so much.

 

[Inchworm]

Hi Marve99,

It doesn't do any fish good to be in a tank with a fluctuating pH. Another thing to consider is that the temperature is a bit warm for the C. metae (bandits.) They do best in a 21-24°C range. (69-75 F.)

If your tank is so densely planted that you can't find dead fish, chances are good that it's not a proper environment for corys whose native environments is pretty bare. You also have an angelfish, which is a cichlid, in the tank.

While none of these factors, by themselves, might be the cause of your trouble, the cumulative stresses they cause might have weakened your fish's immune systems and left them open to opportunistic bacterial infections. This is the underlying cause of many of the problems that effect corys.