Our fish dying

[John E Windsor]

We have had channel cats in the tank for 66 days. In the beginning there were 30 fingerlings, plus 5 goldfish. Within the 1st 2 weeks, 4 of the goldfish made the ultimate sacrifice. The #5 goldfish (we call him Newt, because he will not give up) is still surviving with the catfish. Anyway, in the last 11 days we have lost 4 catfish. Every 2-3 days I have found a half eaten fish floating in the tank. The rest of the fish look and act healthy. I have noticed several that have a calico marking on their backs and I believe this may be an indication of the problem. Any advice?

This is the best pic I could get.

[TCLynx]

That looks like saddle back or Columnaris disease.

Make sure your water quality is as good as possible.

I would salt the system to about 3 ppt  (Don't overdo the salt since catfish can't handle too much.)

http://www.aquaponiclynx.com/salt-for-fish-health

Be sure not to over feed, keep the stress to a minimum, and keep the water quality as good as possible.  Make sure there is some extra aeration and make sure your filtration and circulation is up to the task of keeping the water quality good.

Columnaris tends to rear it's ugly markings on channel catfish if they have been stressed or injured.  It tends to flair up when the water temperatures are between 68-78 F I guess, Perhaps most likely in that temp range as the fish start eating more and people tend to then feed more and often feed a bit too much leaving rotting feed to breed bad bacteria in the tank or cause ammonia spikes which can irritate the catfish's skin thus leaving them open to disease attacks.  Also, any extra swinging around in the tank with nets can scrape the fish and leave them open to disease attacks.

I try to keep netting to a minimum as that stresses them out and can cause direct injury which can lead to the infection getting them.

I have had fish recover from this but the ones that are worst off, get them out.  If a fish becomes ill enough to make it easy to net without stressing the others, pull it out.  If they are all still swimming fast enough to make netting a challenge, then leave them alone to hopefully recover.

[John E Windsor]

Thanks TC! We knew you would have an answer.

Now, are you talking about the total of the water in the system? That would be +/- 1000 gallons, whereas the fish tank itself holds 260 gallons.

[John E Windsor]

@Phil 1. We pump 600 gph through a 260 gallon FT.

          2. The return to the FT is fitted with a Venturi aerator, per your earlier suggestion.

          3. There are 26 small catfish in the tank. In May they were fingerlings. (Plus Newt)

          4. We live in central Florida, so temps are not a major concern this time of the year.

So, I need to clean the bottom of the tank and install some woofers, and add some salt.

         

[TCLynx]

When you salt, you are salting to the water volume in the system.

In aquaponics it would only be necessary to do the water changes if the system was not keeping the nitrates low enough or if something else is going wrong.

If your water tests indicate any water quality problems then perhaps a partial water change is in order, do the water  change before you do the salt or you won't know how much salt is in there.

How much filtration do you have for that 260 gallons?  Keep in mind that a pump that is called a 600 gph pump will only pump that at 0 lift.  As in a 600 gph pump is probably only moving a part of that 600 gallons if you are pumping up 2 or 3 feet through pipes.

As I've said before, I have had fish recover from this but any that are really badly affected usually don't make it and you should remove them from the tank before they actually die if at all possible.  A dead fish in the tank causes water quality issues big time and is a source for other fish to catch the disease from.  If you can't see the bottom of your tank or if there is gunk build up in the bottom of your tank, that is a problem and you need to address it and it could be the cause of some of your issues.

John E Windsor said:

Thanks TC! We knew you would have an answer.

Now, are you talking about the total of the water in the system? That would be +/- 1000 gallons, whereas the fish tank itself holds 260 gallons.

[John E Windsor]

@TC  Our filtration is 4 IBC gravel beds, individually supplied from the FT. They are 16" deep and flood and drain using bell siphons. The top area is always dry and the bottom 2" never drain.

The pump was rated at 960 gph when new, but I have physically measured the flow at 600 gph going into the FT.

The two remaining fish that have the discoloration are not going to allow an easy capture. They act healthy, but look rough.

I just checked my numbers in the water and they look good. pH +/- 6.5; HO3=40-80ppm; NO2=0ppm; ammonia has dropped from 1ppm to +/- .25ppm

Lowe's has Morton (40 lbs) Salt Solar Crystals. That looks like what I am looking for. Now I am a little confused on how to introduce the salt to the system. Do I dissolve some salt in a 5 gallon bucket and then weigh the salt water I need to add or what?

[TCLynx]

Ok good sounds like you got a good pump for the job.

If the fish act healthy and would not be easy to capture, then leave them be and minimize stress by only sticking the net in there if you see one that looks almost dead.

Ok so the ammonia was up before, that could easily have caused the disease outbreak so it's good to hear it's come back down.

Yes the morton solar salt is perfect or their solar pool salt might be even faster to dissolve.

You weigh the salt crystals before you dissolve them in some water and then add the dissolved salt into the system.  Now if you have a sump that has no fish in it, you can simply weigh out the appropriate amount of salt for your total system water volume and add the salt into the sump where it can dissolve on it's own.  But don't put undissolved salt crystals into a tank with fish

John E Windsor said:

@TC  Our filtration is 4 IBC gravel beds, individually supplied from the FT. They are 16" deep and flood and drain using bell siphons. The top area is always dry and the bottom 2" never drain.

The pump was rated at 960 gph when new, but I have physically measured the flow at 600 gph going into the FT.

The two remaining fish that have the discoloration are not going to allow an easy capture. They act healthy, but look rough.

I just checked my numbers in the water and they look good. pH +/- 6.5; HO3=40-80ppm; NO2=0ppm; ammonia has dropped from 1ppm to +/- .25ppm

Lowe's has Morton (40 lbs) Salt Solar Crystals. That looks like what I am looking for. Now I am a little confused on how to introduce the salt to the system. Do I dissolve some salt in a 5 gallon bucket and then weigh the salt water I need to add or what?

[John E Windsor]

Great! Okay, I am on my way to Lowe's for a bag of pool salt. Now, how much salt should I add.

I have one fish in the sump, but our new DWC doesn't have much more than lots of water and rafts. I can pour the salt right into the DWC where it will get pumped into the FT.

[TCLynx]

http://www.aquaponiclynx.com/salt-for-fish-health

you only want to salt to 3 ppt

the above link will give some numbers for figuring out how much salt to weigh out per volume of water.

1 lb of salt per 100 gallons = 1.25 ppt

[John E Windsor]

So, 20# of salt in 1000 gal of water = 2.5 ppt. Damn, that seems like a lot of salt, but I haven't known you ro be wrong yet. Here goes the hail Marys!

[TCLynx]

Yep it does take a lot of salt but a 40# bag is usually between $4-8 so not that outrageous.

and 2.5 ppt sounds like a fine level of salt for channel catfish.  (as long as your source water isn't salty to begin with and provided you haven't been salting before.)

If you know some one with a hydroponics EC or TDS meter, you can dip it in your system water to see if there is much salt to begin with but it isn't all that useful for checking exact salt levels since 3 ppt is likely to be above and beyond it's readable range.

[John E Windsor]

Once again, thank you TC. It has been a week since I added the 20# of salt, and no more dead fish. I did remove the one fish in the pic. He was not going to make it. There was one more that had the markings, but even that one has cleared up. Even Newt seems to be happy that his friends are doing well.

[TCLynx]

Thanks for posting, good to hear it John