Cory Catastrophe

[becky412]

Hello, I need to pick your brains. I have a 36 gallon bowfront and 55 gallon. Both are set up with the same substrate ( pea gravel), cannister filters and 2 power head - one at water line and one low along the back wall as well as artificial and live plants.

My 55 gallon as 12 quarter to half-dollar size juvenile angels (will be thinning out), 4 three inch bushynose plecos and 6 small spotted cory - all living, thriving and happy. Rocks for decor and plant attachment and a faux tree stump for hiding spot(s).

My problem is my 36 bowfront. I am having consistent cory deaths. As I said it is set up mechanically the same. It is stocked with 3 red & blue columbian, 2 lemon and 3 del rio tetra, 2 bushy nose pleco and currently, that I can find, 2 (I think - I can find one) panda's left, some rocks (for plant attachment) and faux rock structures for hiding.

I have lost 6 albino, and 6 panda. I never see them die, I just find them. This morning I was feeding and the lastest loss spiraled to the top of the tank, went back to the bottom, rolled over and died before I could get it netted out and put into a medication bath. When I buy them, I have quarantined them for a couple of weeks and they are fine. I move them to this tank and stuff happens.

Specifics you are going to ask about:

Water source is well and was tested in September and was clear.


API Testing: pH - 7.2; Ammonia - 0; Nitrite - 0; Nitrate - 10; kH - (2 drops) 0-50; gH - (3 drops) 50-100; phos 1.0

Last water change - 9/22 - 50% - stress coat added as well as Seachem prime to help boost back the biological

Last substrate vacuum - 9/22

Cannister filter was opened and rinsed (in tank water) last week.

I have prefilters on intakes - no fish attached.

Water change & substrate vacuum yesterday (9/22) on my 55 - stress coat added as well as Seachem prime to help boost back the biological. Everyone is happy. Cannister was rinsed in tank water last week.

The water in my 55 is crystal clear, the 36 is cloudy.

So, I am at a loss as to what is going on. Anyone have any thoughts?

 

[Aiken Drum]

Your substrate doesnt look very cory friendly. Doesnt explain why they die in one and survive in the other but it maybe the specific species in one are better able to cope than the species in the other

Maybe there is a personality clash with one of the fish in the 36g.

Why are you using 2 different water conditioners? They both do the same job and neither of them do anything to "boost back the biological".

 

[becky412]

Sorry, meant SeaChem stability has beneficial bacteria in it which I use to help boost the beneficial bacteria that may have been removed.

Stress Coat is used for the reason it states - to help the fish maintian their stress coat. Water changes & substrate vacuuming can cause stress.

 

[becky412]

Sorry, meant SeaChem stability has beneficial bacteria in it which I use to help boost the beneficial bacteria that may have been removed.

Stress Coat is used for the reason it states - to help the fish maintian their stress coat. Water changes & substrate vacuuming can cause stress.

 

[Magaratz]

I was losing my corys. My LFS said the bristle nose could be causing stress to them after the lights went out. I returned the bristle nose and the problem ended.

 

[becky412]

Thanks for the info. I dont think that. Is happening since I have plecos in both tanks and the corys in the other tank are all alive and well

 

[Joe_D]

fact is, unlike popular thinking Corys do just fine on gravel.

 

[ghyti]

Yes cories do great on small gravel. Sounds like there is something toxic in the tank, maybe one of the artificial plants. Double check to be sure that there is good circulation near the bottom. Bottom power head stopped? Also make sure you have a little surface agitation to provide good oxygen transfer.

 

[Aiken Drum]

Yes cories do great on small gravel. Sounds like there is something toxic in the tank, maybe one of the artificial plants. Double check to be sure that there is good circulation near the bottom. Bottom power head stopped? Also make sure you have a little surface agitation to provide good oxygen transfer.

That was my point on the gravel. The gravel in those tanks looks overly large and will trap a lot of detritus which the corys might eat. It also looks quite abrasive.

 

[ghyti]

Bad gravel won't kill cories, might wear down the barbels but should not kill. Besides same gravel in the other tank without problems. Got to be something unique to the smaller tank. Cories are on the bottom and other fish are up in the water column so I suspect lack of oxygen or toxic substance at the bottom. Yes could be something trapped in the gravel.

 

[becky412]

Update!!!!! Lone panda cory that was taken from 36 gallon tank and put into 55.......still alive!!!!! Pleco's still okay in 36. Notice that fish are also okay even when they stay at or close to bottom. Such!!!!!! a mystery!!!!!

Did 50% water change yesterday and moved plants and ornaments so that I could vacuum good and also stirred up the gravel quite a bit. All fish (tetra & plecos) survived the disturbance.

 

[becky412]

Yes cories do great on small gravel. Sounds like there is something toxic in the tank, maybe one of the artificial plants. Double check to be sure that there is good circulation near the bottom. Bottom power head stopped? Also make sure you have a little surface agitation to provide good oxygen transfer.

Bottom powerhead is working. I have had another powerhead at top for a while to aggitate the water surface for gas exchange.

 

[Colin_T]

Can you post pictures and a 1 minute video of the Corydoras if/ when they spin/ spiral?

When fish start spinning/ spiraling through the water it is usually caused by a bacterial, viral or protozoan infection in the brain. The infections are normally protozoan and normally caused by a dirty tank, gravel or filter. If the fish have been dying one by one since you got them, they might have had the problem at the shop. Salt can sometimes help stop it spreading but you usually lose the fish that are spinning. If you want to try salt, see directions below.

It's preferable not to move fish from a tank if they are dying for no reason. if they have a disease you can transfer it to another tank when you move the sick fish. Hopefully the Corydoras you moved was free of any illness, but you should monitor the fish in both tanks for the spinning.


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SALT
You can add rock salt (often sold as aquarium salt) or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.

 

[becky412]

There are no more cory in the tank and the survivor is happily living in the 55 and has been since Sept 28. All other fish in that tank (36 gallon)) are doing fine.