Poorly corys: to treat or not to treat...

[Elena82x]

Hello
I'm really torn as to what to do about my poorly cories. I've just moved everything into a 240l tank. It hasn't been cycled but I've moved the old filter in with it in addition to the new one, and couple of rocks, in the hope that it is part cycled. I'm going to check parameters daily and do large water changes as needed. I wanted to get them moved quickly because the cories weren't looking well. (My mollies and guppies have been fine). As one of the possible causes was the substrate I have left it and, thanks to amazing advice on here, have put a new soft river sand in the new aquarium.
So, my issue is that the cories (albino cories) have been losing scales and starting to look an orange colour. I hoped that the new improved environment and substrate would help them but upon moving them I've spotted that they may have red blotch disease. At least one of them has a red blotch near its tail, and another has sort of a red streak towards its tail. I feel really sorry for them like I am massively letting them down! I have read that treating with salt isn't good for cories. I've got some melafix, should I be putting that in urgently? I'm worried that then what little bacteria is in the tank will also be killed off so I've no hope with the cycling. Also I don't know if I should be looking at tetracycline rather than melafix... Or should I just wait and see if the improved environment fixes things. I suspect that the bacterial infection needs treating doesn't it? I've also got molly fry in the tank. I don't have the option to quarantine as I'm using the old filter so they'd be in an uncycled tank.
Thank you for reading.

 

[DragonScales+Doubletails]

I've heard melafix horror stories, hold off on that for now. @Colin_T knows how to deal with these things,

 

[Byron]

First, do not add any "medication" unless you have a very good idea of the issue, and that medication is the safest and most effective. Like most of us, myself included, this means getting advice from knowledgeable individuals. We have such members, but they will need more data to assess things. All additives get inside the fish and cause stress, or much worse, so any added needs to be worth the risk.

Can you post clear photos of the affected fish? And a photo of the entire tank so we can assess things?

What are the water parameters? Parameters refers solely to GH, KH, pH and temperature. The GH and pH especially are important. You should be able to get the GH from your water authority, check their website.

What are the water conditions? These are ammonia, nitrite, nitrate.

 

[Elena82x]

First, do not add any "medication" unless you have a very good idea of the issue, and that medication is the safest and most effective. Like most of us, myself included, this means getting advice from knowledgeable individuals. We have such members, but they will need more data to assess things. All additives get inside the fish and cause stress, or much worse, so any added needs to be worth the risk.

Can you post clear photos of the affected fish? And a photo of the entire tank so we can assess things?

What are the water parameters? Parameters refers solely to GH, KH, pH and temperature. The GH and pH especially are important. You should be able to get the GH from your water authority, check their website.

What are the water conditions? These are ammonia, nitrite, nitrate.

Thank you for your reply.
I've just checked on the GH/KH and it states mod hard 10.5 which I think I've worked out as 180ppm and KH says 151 which I assume is ppm. PH is 7.4. Temp 78f.
Ammonia and nitrite are zero, nitrate currently 5 in new tank but typically around 20.
The previous substrate was what was sold to me as black sand but in unfortunate hindsight more a sharp slate type substance.
In the tank I've got 3 mollies, 5 molly fry, 6 guppies, 8 albino cories and 6 yoyo loaches.
I can't always find the cories but have just found at least one, possibly two, looking like this (photos attached and one of the new tank to follow, only been in it 24hrs the condition was already present)

 

[Elena82x]

Thank you for your reply.
I've just checked on the GH/KH and it states mod hard 10.5 which I think I've worked out as 180ppm and KH says 151 which I assume is ppm. PH is 7.4. Temp 75.5f.
Ammonia and nitrite are zero, nitrate currently 5 in new tank but typically around 20.
The previous substrate was what was sold to me as black sand but in unfortunate hindsight more a sharp slate type substance.
In the tank I've got 3 mollies, 5 molly fry, 6 guppies, 8 albino cories and 6 yoyo loaches.
I can't always find the cories but have just found at least one, possibly two, looking like this (photos attached and one of the new tank to follow, only been in it 24hrs the condition was already present)
View attachment 166753View attachment 166752

View attachment 166751View attachment 166754

 

[Byron]

OK, at this juncture I alert our more expert members than I am in disease-type issues. @GaryE @Colin_T @DoubleDutch

 

[GaryE]

I can't help. Every time I have seen that red streaking, the Corys have not survived it.

 

[DoubleDutch]

Frequent waterchanges and use of Melafix is often advised for Red Blotch (not 100% sure it is that but it won't harm them.).

Though Melafix doesn't do much strangely Corys seem to benefit from it adapting to new waterconditions.

 

[itiwhetu]

Nitrates at anything apart from zero are too high for Cory's

 

[Colin_T]

I can't tell anything from the pictures due to them being blurry and dark.

You won't be able to get tetracycline (antibiotic) in the UK unless you see a vet.

If they have a minor bacterial infection, you can try salt.

------------------
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.

 

[Colin_T]

Nitrates at anything apart from zero are too high for Cory's

Good luck trying to keep nitrates at 0ppm in an average aquarium.

Most people try to keep them as close to 0ppm as possible and below 20ppm at all times. A nitrate reading of 20ppm is considered the cut off limit for invertebrates, and should also be the maximum limit for fish.

 

[itiwhetu]

Good luck trying to keep nitrates at 0ppm in an average aquarium.

Most people try to keep them as close to 0ppm as possible and below 20ppm at all times. A nitrate reading of 20ppm is considered the cut off limit for invertebrates, and should also be the maximum limit for fish.

I am convinced that the most deadly or harmful thing in your tank is the Nitrate level. If you can maintain your tank at near zero Nitrates, then all your other problems will go away.

 

[Colin_T]

I am convinced that the most deadly or harmful thing in your tank is the Nitrate level. If you can maintain your tank at near zero Nitrates, then all your other problems will go away.

Ammonia and nitrite are more harmful.

 

[Elena82x]

Thank you everyone for your advice

 

[Elena82x]

I can't tell anything from the pictures due to them being blurry and dark.

You won't be able to get tetracycline (antibiotic) in the UK unless you see a vet.

If they have a minor bacterial infection, you can try salt.

------------------
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.

This photo may be clearer