No signs of illness but flashing. Suffering deaths.

[lpoolck]

Info:
Ammonia 0, Nitrite 0, nitrates 20ppm, PH 6.8-7.2
New tank which was cycled before adding fish. Fish all introduced at same time and been in for 3 weeks.
X6 peppered Cory's
X3 Amano shrimp (not seen one for a while)
X16 white cloud mountain minnows
Daily testing since tank was cycled is showing ammonia always 0, Nitrite always 0, nitrates between 10ppm-30ppm depending on time since last water change. I've also tested after feeding to explore any ammonia spikes. Again same results.
200 litres, external canister, well planted, fluval stratum and corse sand substrate, bogwood and inert river stones as hardscape.

Symptoms:
Flashing only in minnows.
I see some minnows spit out some flake food. They don't do this with live food or bug pellets. Spitting made me think it was another symptom of flukes, but potentially may be food preference due to no issues with eating other foods.
One minnow which is still alive has had white poo at times. Again could be internal parasites but current treatment should also cover this.
X4 are pale compared to others but they were like that at shop and been like that since. The stock the store had were from 2 different deliveries. None of the pale ones have died. I just assumed these would colour up and the lack of colour was due to stress of being in store.
Cory's are absolutely thriving. Feed well, growing well.
Amano's are either hiding or have died. Not seen any since day 5 of them being introduced. No signs of any remains if dead.

Deaths:
X1 minnow 7 days ago
X2 minnows 6 days ago
X1 minnow today

The only sign other than flashing I'm getting is around 1-2 hours before death. The fish will swim in an area of the tank with low flow. During this time breathing is normal. Then all of a sudden the fishes breathing will increase and the fish will float up to surface and be on its side before dying within seconds/minutes.

Treatment:
Fluke solve 4 days ago. Noticed less flashing yesterday and day before, flashing back today. Flashing is not constant, and not all the minnows are doing it.

Any ideas ?

 

[GaryE]

It's not obvious. With 3 weeks in the tank, odds are you are having quarantine losses. I usually QT 6 weeks, if not longer. But what is killing them?
I doubt flukes. I'd be more inclined to look at Oodinium (velvet), but white clouds aren't the usual hosts. They could have had gill damage from ammonia, in shipping to the store. Are the gills redder?
In the quarantine period, there are all sorts of weird bacterial illnesses they can be carrying. Some spread, some don't, and all are very hard for aquarists to identify.
Spitting food is usually chewing - most fish have their teeth on the roof of the mouth and top of the throat, so they drag it in and out to rub it up against the teeth.

 

[lpoolck]

Thank you for your reply, I appreciate it. As it's a new tank, it's effectively a QT tank I guess?

I've looked up velvet and I see no dusting or removal of the slime coat. The tank light is now off and I've shone a flashlight at the fish and see no velvet/flecks. However I'm not going to rule it out as I read on one site it can kill without external signs (dusting etc).

No, there's no notable redness of the gills.

With regards to the spitting. Even very small broken up flakes which you think would require little/no chewing can be spat back out.

 

[GaryE]

Watch the spitting. They may dislike the food, but til it's soaked, they'll often work over even tiny pieces. It's a behaviour that often stresses new aquarists.

I always try to imagine humans if we thought there were ten or so diseases or parasites to be concerned about. That's about where we stand with fish care. We can say it's bacterial, but what bacteria? The choice is enormous. Often we simply have to watch bad things happen. We do our regular weekly water changes and hope. There are remedies on the market for us - they don't help the fish but they make us feel like we're doing something. Most of the time, we aren't.

 

[Colin_T]

Pictures and video of all the fish?
Upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally so the footage fills the entire screen and you don't get black bars on each side.

 

[lpoolck]

Pictures and video of all the fish?
Upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally so the footage fills the entire screen and you don't get black bars on each side.

I'll upload a video tonight

 

[lpoolck]

Videos attached

 

[Colin_T]

any video of the fish rubbing?

 

[Milkie789]

What is the mineral hardness or GH level?

 

[lpoolck]

any video of the fish rubbing?

Got a video of the Cory looking like he was rubbing (bottom right) late last night. Cory's have never been affected until now

With regards to the minnows I'll try get one. It's hard to get as it's not frequent and it's a big tank so hard to capture. Basically they will often go up to a plant leave, bogwood, or rock and rub their side. I have seen on one occasion they run their belly.

 

[lpoolck]

What is the mineral hardness or GH level?

My test kit doesn't do GH or mineral hardness. I know that in generic terms my water is soft to medium.

My plants are thriving and showing great grow in only 3 weeks, and as you can see my fish aren't lethargic. So I assume I have good enough levels?

 

[Milkie789]

My test kit doesn't do GH or mineral hardness. I know that in generic terms my water is soft to medium.

My plants are thriving and showing great grow in only 3 weeks, and as you can see my fish aren't lethargic. So I assume I have good enough levels?

Yeah, I’d say you’re fine in terms of GH. I had a similar problem where my fish were dying all of a sudden and I found out it was because my GH was ridiculously low.

 

[Colin_T]

If they are just rubbing occasionally, it's probably a minor external protozoan infection. It could be velvet, costia, chilodonella or trichodina.

You can treat velvet with heat, 30C (86F) for 2 weeks or at least 1 week after they stop rubbing.

You can treat the other 3 external protozoan infections with salt. See directions below.

If you don't want to use either of those, you can use a medication with Malachite Green (aka Victoria Green). However, Malachite Green isn't as safe as salt or heat.

If you use heat, salt or chemical based medications, increase aeration/ surface turbulence to maximise oxygen levels in the water.

--------------------

SALT
Using Salt to Treat Fish Health Issues.
For some fish diseases you can use salt (sodium chloride) to treat the ailment rather than using a chemical based medication. Salt is relatively safe and is regularly used in the aquaculture industry to treat food fish for diseases. Salt has been successfully used to treat minor fungal and bacterial infections, as well as a number of external protozoan infections. Salt alone will not treat whitespot (Ichthyophthirius) or Velvet (Oodinium) but will treat most other types of external protozoan infections in freshwater fishes. Salt can treat early stages of hole in the head disease caused by Hexamita but it needs to be done in conjunction with cleaning up the tank. Salt can also be used to treat anchor worm (Lernaea), fish lice (Argulus), gill flukes (Dactylogyrus), skin flukes (Gyrodactylus), Epistylis, Microsporidian and Spironucleus infections.

You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) 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.

 

[lpoolck]

If they are just rubbing occasionally, it's probably a minor external protozoan infection. It could be velvet, costia, chilodonella or trichodina.

You can treat velvet with heat, 30C (86F) for 2 weeks or at least 1 week after they stop rubbing.

You can treat the other 3 external protozoan infections with salt. See directions below.

If you don't want to use either of those, you can use a medication with Malachite Green (aka Victoria Green). However, Malachite Green isn't as safe as salt or heat.

If you use heat, salt or chemical based medications, increase aeration/ surface turbulence to maximise oxygen levels in the water.

--------------------

SALT
Using Salt to Treat Fish Health Issues.
For some fish diseases you can use salt (sodium chloride) to treat the ailment rather than using a chemical based medication. Salt is relatively safe and is regularly used in the aquaculture industry to treat food fish for diseases. Salt has been successfully used to treat minor fungal and bacterial infections, as well as a number of external protozoan infections. Salt alone will not treat whitespot (Ichthyophthirius) or Velvet (Oodinium) but will treat most other types of external protozoan infections in freshwater fishes. Salt can treat early stages of hole in the head disease caused by Hexamita but it needs to be done in conjunction with cleaning up the tank. Salt can also be used to treat anchor worm (Lernaea), fish lice (Argulus), gill flukes (Dactylogyrus), skin flukes (Gyrodactylus), Epistylis, Microsporidian and Spironucleus infections.

You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) 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.

Many thanks for this. Most my research states to only use salt for up to 48 hours with Cory's. Do you have any first hand experience with treating Cory's with salt for up to 2 weeks?

I had another sick minnow on Tuesday, he looked like he was just about to pass (floating sideways at top of the tank) so I put him into a quarantine tank with salt in it and he has steadily been making progress. So I do believe salt is the way to go. I'm just worried about how long I can keep it in the tank with the Cory's due to conflicting information around timescales.

 

[Colin_T]

Corydoras and all freshwater fishes are fine with 2 heaped tablespoons of salt for every 20 litres (5 gallons) of water, for 2 weeks. It's the dose rate I use and have been using that since the 1980s.