My Corydoras are slowly dying

[N_F_S]

Before start with the problem, I will post the main tank information.

Tank

• 170cm long x 50 cm wide x 60 cm tall
• 510L

Current Stock

• 5 Guppy Endler
• 5 Guppy
• 15 Tetra Cardinal
• 6 White Fin Tetra
• 10 Black ghost Cardinal
• 2 Ancistrus
• 10 Otocinclus (already lost 2)
• 10 Corydoras Sterbei
• 10 Corydoras Julli (already lost 1)
• 6 Corydoras Panda (already lost 1)
• 3 Corydoras Black Venezuela (already lost 1)
• 1 Garra Flavatra
• 20 Amano Shrimp
• 20 Red Cherry Shrimp

Maintenance:

• During 1st mouth - 60% water Change every other day
• Next 2 weeks - 60% wc every two days
• Next 2 weeks - 60% wc even 2x week
• After 2 months until now - 60% wc 1x week

• Never clean my bio media (sachem Matrix) and 1 bag Seachen Purigen, to avoid lose beneficial bacteria in the first months
• Cleaning Pre Filter Sponges every other week

Water Chemistry - Since I introduced fish, ammonia are always 0, nitrite 0 and nitrate 5 during nigth ate the end of the day (reach 10 after add ferts).
PH - 6,6
KH - 3
GH - 5

Since, my plants eats lot of nitrate, I need to dose Tropica Specialized when Nitrate are 0. Since Tropica Specialized has nh4no3 (ammonium nitrate), when I dose the week dose (20 Pumps), I have NH4 0,25 for 2 hours, and 0,15-0,2 nitrite 6h before all reach 0 again.

Now, the problem. All my Corydoras are acting strange, with a pale or skin deformation and fin rot.

My last introduction was 4 black Venezuela Corydoras and 10 Sterbei 2 weeks ago. I have made an mistaking during the acclimatisation of the Black Corydoras, because the plastic bag drawn a little, and some water of the bag mix with water of my tank.
One day after the introduction of black Corydoras, one of them died (first stoped on the bottom and before died, started to swimming in circles and spinning without direction). 3 days after this, all my active Corydoras started to lay down on the bottom, most of the time, and only active during feeding or right after a water change.

After this, I stay alert and observing the corys everyday. No sign of fin rot, skin problems, white spots or cotton, but 1 week later (3 days ago), lost one Julli. Again, no sign of any strange external problem, and only missing color (or skin) between gill and fin, but could be eaten by the Amano shrimp.

Yesterday, I have spotted the first external sign, 1 julli with strange side skin, seems all scales are jumping.
Today, I have spotted one Cory Panda, with fin rot and strange side skin also.

When I look to my corys, I have different signs, some seems red belly, other pale or strange skin.
I took some photos, and ask some help in one lfs, and the say to dose Myxazin, and apply only to sick fish on other tank.

Through this path, I lost two Otocinclus, but I don't relate with this, because my lfs told me this fish starving without algae and some don't eat pellets and die. My tank don't have a lot of algae right now, and I have to start to feed ancistrus with zucchini because they start to eat some plants.
So, all other fish and shrimp (except maybe for Otocinclus), are fine without signs of feeling bad.

Before start to dose meds, as sugested by lfs, I want to know your opinion.

Note: One black Venezuela has a white mark in the head.

Some pictures attached.

Videos:

 

[FishGuest5123]

I stopped reading at needing to add something when your nitrates are 0 and you then have no trite. You should always have 0 nitrite and I 0 nitrate is fine with heavily planted tank. Am I misunderstanding???

 

[itiwhetu]

I am going to take a guess that adding Tropica Specialized to your tank you are also adding salts. Corys don't like salt. So my guess is that the two are related.

 

[mrsjoannh13]

I'm no expert but just adding a couple of things I thought of from reading your post and looking at photos. First, you seem to have gravel substrate. Corys need sand substrate. I am not sure that this is causing their issues currently but over time they can have issues with their barbels from gravel. Second thought is that your pH at 6.6 may be too low. If they are coming from a pet shop or breeder that had higher pH the lower pH of your tank may be difficult for the fish to adjust to.

One other thought / question - can you tell us about food? Is enough food getting down to the corys to sustain them and keep them healthy?

Is your tank heated? If so, to what temperature?

Hopefully others with more experience can weigh in.

 

[Colin_T]

My last introduction was 4 black Venezuela Corydoras and 10 Sterbei 2 weeks ago. I have made an mistaking during the acclimatisation of the Black Corydoras, because the plastic bag drawn a little, and some water of the bag mix with water of my tank.
One day after the introduction of black Corydoras, one of them died (first stoped on the bottom and before died, started to swimming in circles and spinning without direction). 3 days after this, all my active Corydoras started to lay down on the bottom, most of the time, and only active during feeding or right after a water change.

This is why you should always quarantine any new fish, plants, shrimp or snails for at least 2 (preferably 4) weeks before adding them to an established aquarium.

Fish spinning in circles is caused by a bacterial or protozoan infection in the brain. It regularly occurs in tanks with lots of rotting matter (gunk) in the filter and or substrate, and in tanks that don't get enough water changes.

The fact this happened 24 hours after adding the fish to your tank suggests the fish were sick before you got them, and they have introduced a protozoan infection into the tank.

The catfish with the damaged dorsal fin looks like it is being eaten by an external protozoan infection too.

----------------------
I would clean the filter (including the Purigen and Seachem Matrix) and any exposed areas of gravel (with a gravel cleaner). Do a massive water change and then add some salt.

----------------------
SALT
You can add rock salt (often sold as aquarium salt) or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons 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 but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (2 heaped tablespoons per 20 litres) will not affect 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.

----------------------
You can try leaving the lights on for an extra 1 or 2 hours each day to encourage algae for the Otocinclus and suckermouth catfish. Alternatively, you can grow algae on rocks or ornaments outside and bring them in each week for the fish to graze on.

Get a large plastic storage container and put it outside in the sun. Fill it with dechlorinated tap water and add 1 level tablespoon of lawn/ garden fertiliser for every 20 litres of water. Mix it up and then add some smooth river rocks or ornaments. Leave the rocks/ ornaments in the water until they get covered in green algae, then move them into the aquarium for the fish to graze on.

----------------------
The pH and GH are a bit low for guppies and Endlers but is fine for the other fishes. Guppies do best in water with a pH above 7.0 and a GH above 200ppm.

 

[N_F_S]

I stopped reading at needing to add something when your nitrates are 0 and you then have no trite. You should always have 0 nitrite and I 0 nitrate is fine with heavily planted tank. Am I misunderstanding???

Plants needs nitrates, and even when I add ferts with nitrogen, they disappear after 2/3 days. So I think my plants need it. I'm wrong?

I am going to take a guess that adding Tropica Specialized to your tank you are also adding salts. Corys don't like salt. So my guess is that the two are related.

It's in trace quantities. I know more cases with this kind of ferts and happy corys. But I can try to don't dose during 1 one or so.

I'm no expert but just adding a couple of things I thought of from reading your post and looking at photos. First, you seem to have gravel substrate. Corys need sand substrate. I am not sure that this is causing their issues currently but over time they can have issues with their barbels from gravel. Second thought is that your pH at 6.6 may be too low. If they are coming from a pet shop or breeder that had higher pH the lower pH of your tank may be difficult for the fish to adjust to.

One other thought / question - can you tell us about food? Is enough food getting down to the corys to sustain them and keep them healthy?

Is your tank heated? If so, to what temperature?

Hopefully others with more experience can weigh in.

My tank are 60% ADA Soil covered with Monte Carlo carpeting plant, I don't think it can damage the barbels, and 40% of ADA Sand (La Plata). I only have gravel in the mixing zone (in the boarder line, where sand mix with ADA Soil.

This is why you should always quarantine any new fish, plants, shrimp or snails for at least 2 (preferably 4) weeks before adding them to an established aquarium.

Fish spinning in circles is caused by a bacterial or protozoan infection in the brain. It regularly occurs in tanks with lots of rotting matter (gunk) in the filter and or substrate, and in tanks that don't get enough water changes.

The fact this happened 24 hours after adding the fish to your tank suggests the fish were sick before you got them, and they have introduced a protozoan infection into the tank.

The catfish with the damaged dorsal fin looks like it is being eaten by an external protozoan infection too.

----------------------
I would clean the filter (including the Purigen and Seachem Matrix) and any exposed areas of gravel (with a gravel cleaner). Do a massive water change and then add some salt.

----------------------
SALT
You can add rock salt (often sold as aquarium salt) or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons 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 but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (2 heaped tablespoons per 20 litres) will not affect 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.

----------------------
You can try leaving the lights on for an extra 1 or 2 hours each day to encourage algae for the Otocinclus and suckermouth catfish. Alternatively, you can grow algae on rocks or ornaments outside and bring them in each week for the fish to graze on.

Get a large plastic storage container and put it outside in the sun. Fill it with dechlorinated tap water and add 1 level tablespoon of lawn/ garden fertiliser for every 20 litres of water. Mix it up and then add some smooth river rocks or ornaments. Leave the rocks/ ornaments in the water until they get covered in green algae, then move them into the aquarium for the fish to graze on.

----------------------
The pH and GH are a bit low for guppies and Endlers but is fine for the other fishes. Guppies do best in water with a pH above 7.0 and a GH above 200ppm.

Thank you Colin_T.

Yes, I understand the quarantine, I'm building a quarantine tank right now.

Thank for your idea of extend the light period.

Regarding the protozoan infection, thank you for your help and diagnoses. So, don't dose Myxazin, right?

 

[FishGuest5123]

Plants needs nitrates, and even when I add ferts with nitrogen, they disappear after 2/3 days. So I think my plants need it. I'm wrong?


It's in trace quantities. I know more cases with this kind of ferts and happy corys. But I can try to don't dose during 1 one or so.



My tank are 60% ADA Soil covered with Monte Carlo carpeting plant, I don't think it can damage the barbels, and 40% of ADA Sand (La Plata). I only have gravel in the mixing zone (in the boarder line, where sand mix with ADA Soil.



Thank you Colin_T.

Yes, I understand the quarantine, I'm building a quarantine tank right now.

Thank for your idea of extend the light period.

Regarding the protozoan infection, thank you for your help and diagnoses. So, don't dose Myxazin, right?

My tank is fairly heavily planted and I only 1/2 dose fert’s once a week or week and a half. I started doing that after I lost 2 pandas at separate times after dosing full strength.

 

[N_F_S]

thread update.

I have spotted my Corydoras swimming sideways to touch with the body on sand, so they really feel bad.

The problem seems are expanding to the other fish too. I have seen one guppy with strange color, and my cardinal tetras, are pale, with white color, and an strange dark zone in the belly.

More photos attached.

Do you think the problem are the same?

 

[N_F_S]

This is why you should always quarantine any new fish, plants, shrimp or snails for at least 2 (preferably 4) weeks before adding them to an established aquarium.

Fish spinning in circles is caused by a bacterial or protozoan infection in the brain. It regularly occurs in tanks with lots of rotting matter (gunk) in the filter and or substrate, and in tanks that don't get enough water changes.

The fact this happened 24 hours after adding the fish to your tank suggests the fish were sick before you got them, and they have introduced a protozoan infection into the tank.

The catfish with the damaged dorsal fin looks like it is being eaten by an external protozoan infection too.

----------------------
I would clean the filter (including the Purigen and Seachem Matrix) and any exposed areas of gravel (with a gravel cleaner). Do a massive water change and then add some salt.

----------------------
SALT
You can add rock salt (often sold as aquarium salt) or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons 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 but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (2 heaped tablespoons per 20 litres) will not affect 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.

----------------------
You can try leaving the lights on for an extra 1 or 2 hours each day to encourage algae for the Otocinclus and suckermouth catfish. Alternatively, you can grow algae on rocks or ornaments outside and bring them in each week for the fish to graze on.

Get a large plastic storage container and put it outside in the sun. Fill it with dechlorinated tap water and add 1 level tablespoon of lawn/ garden fertiliser for every 20 litres of water. Mix it up and then add some smooth river rocks or ornaments. Leave the rocks/ ornaments in the water until they get covered in green algae, then move them into the aquarium for the fish to graze on.

----------------------
The pH and GH are a bit low for guppies and Endlers but is fine for the other fishes. Guppies do best in water with a pH above 7.0 and a GH above 200ppm.

One more help Colin_T please. When I went to my lfs, I asked for aquarium salt to use to combat the problem, they give me the following product:

https://www.seachem.com/brackish-salt.php

when I checked the doses, they seems a lot less than you suggested (1tbsp to 40L). this product can work in this case?

 

[Colin_T]

It's a bit hard to tell with the cardinals but if their muscle tissue under the skin is turning opaque or white, they have a microsporidian infection (muscle wasting disease). It can usually be treated with salt (sodium chloride, 2 heaped tablespoons per 20 litres).

I'm not sure what's in the SeaChem salt but their website says it contains no buffering compounds but does contain more than just sodium chloride. Personally I just use swimming pool salt because it's cheaper.

If you want to use the SeaChem salt, use it at 2 heaped tablespoons per 20 litres.

 

[N_F_S]

Two more deads. One cardinal and one julli.

the julli has a red tail inside. I don’t know if the red zone happen before or after dead.

pictures

 

[mbsqw1d]

Is your water source straight from the tap, no water softeners in the mix is there?

 

[N_F_S]

Is your water source straight from the tap, no water softeners in the mix is there?

Directly from tap water, and use Prime as water conditioner

 

[Colin_T]

If you have some Waterlife Myxazin, start treating the tank with that now.

Remove carbon from the filter.
Increase aeration.
Wipe the inside of the glass down.
Clean the filter if it hasn't been done in the last 2 weeks.
Do a big water change and complete gravel clean before treating (assuming you didn't do one the other day).

You can use salt and Myxazin together.

 

[Utar]

I am so sorry to hear about your beloved fishes dying. You have already gotten advice from people far more knowledgeable than I am, so I wish you the best and hope you can save as many of your fish as possible.