Backyard Aquaponics
A place to discuss aquaponics

Hello everyone,

So I have recently acquired a bunch of mixed tilapia fish and have them in a small quarantine system to make sure they are okay. Over the first week, a quarter of them have died. This week, they aren't dying but they seem to be sick. I don't have any idea if they are or aren't and what to do about it before I move them into my larger system and get everything else infected. They have some fuzz that looks like cotton or small spider webs. Here are some pictures. Any ideas whats wrong and what I should do?

Also, does anyone know what type of tilapia these fish are.

Thanks in advance to anyone that can help.

Cheers

Sorry your fish are having troubles. Probably should salt the water in the quarantine system with 3 parts per thousand of salt (NaCl) (on up to 6 ppt). It may not get rid of the infection causing organism(s) but it will at least help the fish build a slime coat and that could help them fight this off. After that it's just a waiting game unless you can determine what's causing this .

what is the situation with your water ?

Fish are very susceptible when they have been stressed (eg. transport and new location).
There is also some stress if the water conditions are different from the transport system to the tank setup.

Is the small system/tank adequately aerated and filtered ?

As per Scotty salt would help - should have been done when first arrived.
(ideally for a little time before fish added)
consider a brief high salt bath and then into a new tank that has been salted.
The issue will be present in current water if you simply put fish back

n.b. did you add water from the transport to your temporary tanks ?
many things are always present in a system but can expand rapidly when things go a bit wrong and/or fish are stressed.

_________________
.
Darren ( dlf_perth )

May the fish sh*t and the plants grow.....

Thank you for your sympathy. I have salted at 2.5 ppm over the past week, also I have been doing water changes daily to keep everything low. I have also performed a potassium permanganate treatment for 4 hours the day after I moved them in and about ten days later.

My main issue is trying to figure out what the white fuzz is on them and get a diagnoses before moving them again. I am assuming the white stuff is Columnaris (Flexibacter columnaris) Cotton-wool, Mouth Fungus. If so, I don't know how I can treat this problem without harming my beneficial bacteria too much. Any ideas?

Thanks dlf_perth for your reply.

Basically to answer your questions:

1. The water quality is not ideal by any means, but I am doing water changes every day. The first issue with this is that I have to add a large mass of fish to a quite small quarantine system. 52 kg of tilapia were added to a system that is 7 cubic meters total water volume including bio-filters. The bio-filters alone are about 4 cubic meters. I am performing water changes daily, approximately 1.5-2 cubic meters per change with fresh water. I am also salting the system to get the salt back to 2.5 ppm each time. Salt added in intervals not to shock the fish. About 15 kg of the fish have died so far. Deaths have stopped over the past week, but the symptoms in the pictures remain.

2. A brief salt bath for all the fish will be a bit complicated as there are about 400 fish and they are very large (approximately 100 grams each) I would not know how to keep track of which ones I have removed and dipped. Also, I am worried this will stress them too much.

3. When the fish were introduced to the quarantine, there is a possibility that a small bit of water was added, but that is less than half a liter total during the whole process. Also I dipped the fish in potassium permanganate prior to putting then in the system.

As I mentioned to scotty, I am trying to figure out whether or not the disease or illness they have will go away and I am okay to add the fish to my main system, or is there something I should do first before I move them. I am thinking that they have Columnaris (Flexibacter columnaris) Cotton-wool, Mouth Fungus, but I have no way of knowing for sure other than checking with the experience of the folks here on the forum for help.

Any ideas?

hard one - as is case anytime you get an outbreak like this.
sadly there are quite a few posts of this nature - animal husbandry is a delicate balance and things often go bad fast when it goes wrong.

If you have another tank/container then you could use water from AP fish system and then salt that.
Then move fish through through a concentrated salt bath (as a shock treatment) and then in to the new system.
In that case you would focus on the healthiest of the fish.

You get various ideas from internet pages.
Even if not Columnaris it will be some form of bacteria or fungus.

The most important thing is don't put these fish anywhere near your system.
And make sure to sterilise everything you use before using it anywhere else.

_________________
.
Darren ( dlf_perth )

May the fish sh*t and the plants grow.....

I'm guessing you're right about this being columnaris but it's tough to see the masses and how they look. A lot of what I'm seeing is slime produced by the fish in response to an infection. If you can get access to a microscope it should be relatively easy to tell the difference between columnaris (which is a motile bacteria) and a fungus. Columnaris will be groups of individual cells while with the fungus you'll see long filaments called mycelium sometimes with cross walls along the mycelium (called septate mycelium) and sometimes without (non-septate). You may have some of both in this group of fish so try to check more than one.

2.5 ppm is insufficient to kill columnaris from what I'm seeing online. I do see where a treatment level of 3 parts per thousand has worked on channel catfish.

How large is this quarantine system?
How big is the filter?
How do the ammonia and other parameters look? Water temp?
How is the circulation and oxygenation of the water?
Any waste build up in the tank?

I'm thinking a combination of stress and poor water quality (even with the water changes). The obvious course is to improve the water quality and reduce the stress. Columnaris doesn't like the higher salt levels and they help with stress as well. Keep adjusting the salt levels back up when you do water changes but go to the higher levels. If you have to put them in your main system because you can't keep the water quality where you need it, get a UV sterilizer and hook it up to the system to cut down on free floating/swimming organisms in the water (just run it during active infections). I'd have it recirculate the tank water through the UV although you'll never eliminate all the organisms this way.