Backyard Aquaponics
A place to discuss aquaponics

Hi there,

I'm new to the forum and am a first time poster. This is quite a long saga but I am trying to include enough relevant detail to give the full picture......

My fish are dying suddenly and I need help!!!

I've had my system going since August of 2015 and have built two separate systems out of barrels that are on my back patio. Each barrel is about 22" across and I have about 20 gals on water in each system. I had six small goldfish in one system, and four in the other system (this one has fewer plants to uptake the waste). The last time I introduced any fish was in December.

My system was humming along and at this point I was doing infrequent checks of pH, ammonia, nitrite and nitrate. My levels were always around pH 7.4-7.6, amm=0 ppm, nitrite=0 and nitrate =40+. A few weeks ago I noticed one of my fish was acting weird and hanging out near the surface. She also had a very small lesion on her side. Thinking it might be bacterial I got some Melafix after work but came home to a dead fish. I treated the tank anyway since I didn't want the other fish to become infected with the same thing. I was dosing daily as directed on the bottle, and while i was checking my tanks one morning about a week later I saw that my largest and oldest goldfish looked like it had dropsy! It was bloated and looked like a pine cone. I removed it from the tank and put it in quarantine. I tested the tank levels and everything is normal! That fish is still alive although I'm not sure for how much longer.

That same week a fish in my other tank died suddenly! Levels were all clear in that tank as well! After that death I noticed one of the fish was breathing very hard and would freak out at very small things. I quarantined that one as well. Two more fish died within the week despite dosing with Melafix, Pimafix and adding aquarium salt.

I study fish physiology and my scientific nature led me to necropsy one of the dead fish. Nothing stood out except that the inside of the visceral cavity had small black spots. I thought maybe that was evidence of parasites and went out to get a parasite treatment. Since there wasn't evidence that it was fungal I stopped dosing with Pimafix and began dosing with the parasite treatment and Melafix. A few days later another fish died. It literally went from swimming to dead within a few hours! I've been doing water changes on the quarantine tanks and adding water to the main tanks as well. I always test the parameters of my top off water before I add it.

Yesterday I came home from work to one more dead fish....I necropsied that one as well and am still at a total loss. Nothing stood out, no black spots on the flesh or anything, although I guess many parasites or bacterial infections could be too small to see with the naked eye, but I have been dosing for those issues. I would say that the only abnormality was a slight bit of abdominal swelling which was true for both of the fish I necropsied....Is that a kidney issue? Why would it effect fish in both tanks and so suddenly? This fish also had slightly paler gills than normal...not sure what that could mean. None of the fish have any external symptoms, in fact they look like picture perfect (if only slightly swollen) goldfish!


HELP!! I'm at a total loss and am now down to just 4 out of my 10 fish friends.

Any suggestions or feedback would be helpful. I also have pictures of the necropsies if requested.

Thanks!!!

Could be lots of things

Post up some pics of your system, that might give someone some ideas. In the meantime, increase the aeration on the tanks if you can.

Are the fish flashing (trying to rub something off on the bottom of the tank so their side flashes the light toward you)? This is one indication of parasites.
Are you seeing any gasping at the surface. This could indicate low oxygen levels or problems taking in oxygen.
Have there been large changes in the water temp?
Have you added salt to the tank to help the fish with stress or parasites?
Is the tank covered and safe from preditors?
Is there lots of algae?
Did you notice if the spots inside the goldfish were hard or soft?

The bottom line is you may never know what happened but it might be possible to get an idea.

Lots aquarium medications reduce the oxygen levels in the water and recommend adding extra aeration on the bottle. Have you got any air stones in at the moment? and if you look closely at the fish are they breathing faster than normal?

..
Is this an AP system..
I would not want to use aquarium products (treatments) in an AP system where I was going to eat the produce...

Now I would have been more inclined to add SALT

yep, photos.

Have you added anything out of the ordinary to the tank or the beds leading up to this? Or something found it's way in?

Where do you get your top up water? town, well, bore,rain?

Dropsy is bacterial...(which you know and I posted it for other readers benefit not to be insulting).

Are you doing water changes?
Overfeeding ..is your food bad?
Another cause could be fluctuations in water temps.

I'd go with Salt and (same temperature) water changes...

HEADS UP- Some of the attached photos are graphic

Hi all, thanks for the replies!

I have not noticed any fish flashing but a couple were breathing hard. No gasping at the surface either from what I saw but definitely breathing harder. Both tanks have aquarium salt and very little algae. I have an air stone in each tank and the system is flood and drain so every time it drains it aerates the water a bit. Do I need more aeration? None of the medications specified needing more air in the tanks.

I should mention that I live in San Diego and we don't generally have huge temperature swings. But we have had a couple of warm days and the tanks did get a bit warmer than usual- maybe only a few degrees. How much of a temp swing can they handle?

I have been topping off the tanks with water from the hose. Our water is very buffered and has around .5 ppm of ammonia so I always add AmQuel which removes ammonia, chlorine and chlorides. It also comes out of the tap at a pH around 8.4 so I use pH down. Since it takes a while to buffer and equalize pH, I usually leave the top off tub to sit for a few hours before I test it and add it to my system. My tanks are currently around pH 7.6. I have used some spring water in the past as well but since the pH is around 7.0 I usually have to add hose water anyway or just use very little spring water so as to not shock the pH too quickly.

My food is only a few months old and I have only been feeding a pinch a day (some days the fish didn't eat). I've also been cleaning out the pump filter every other day to keep it clean and netting out any extra food or junk on the bottom of the tanks.

I had a friend/aquarist look at the necropsy photos and he thought it could be bacterial but that the Melafix wasn't strong enough. I bought some tetracycline and added the first dose on Saturday. I added the second dose on Sunday, went for a bike ride and came home to another dead fish. I necropsied that one as well (photos attached) and she had the same black spots as the first one I necropsied (but the second fish didn't have them). The spots seemed soft and were easy to scrape away. She did not smell particularly bad when I cut her open so I'm not sure if its bacterial or not. The only notable thing was an enlarged gallbladder which makes sense since she wasn't really eating. There are now no more fish in one of my systems and only three left in the other (one of which is my fish with dropsy).

For a while I was not doing water changes, only topping off the water and testing to make sure the pH, ammonia, nitrite and nitrate were within range. Everything always tested well so I wasn't too worried until this all started. My nitrate was occasionally 40+ ppm, could that have triggered any of this?

I'm pretty discouraged at this point and as much as I love fish it might be better for me to not have them if I can't figure this out.

The third photo of the fish looks as if it is egg bound.