FISH PROBLEM - Hybrid Striped Bass

[nwestwood]

I added 130 fingerlings to my 300 gallon system last Thursday. A few were belly up the next day, and I chalked it up to travel loss. Then a few more the next day and the next. Sunday, I tested the water and Ammonia was 1.0, Nitrites were .5 and Nitrates 30ppm,PH of 7.0 temp 74 (23C).

The Ammonia may have spiked higher in prior days and I didn't catch it. I did a partial water change and the next day, the levels were back to normal, but there were more fish deaths (7). Then Monday 5 dead, Tuesday 4 dead and this morning 8 more.

The nitrate levels are going up, It looks like they are over 50-60ppm now (normally they run 10ppm). I did another partial water change this morning.

The fish begin by starting to swim slower, tipping side to side and upside down. If you catch them they still respond and try and get away. They appear to have a mucous or fuzz in front of the eyes (maybe from the eye socket). If I catch these, the fuzz comes off (like wiping a runny nose kid). When they die, it's with their mouths wide open and they sink to the bottom. At no point are they gulping on the surface, so I don't think its oxygen.

The dead ones look like they have blood vessels in the head and front that are burst (discolored through the skin, not seen in healthy fish).

The DO levels are 7.0+ in the day and early morning test show its 5.5+ early.

Is this still a result of ammonia levels spiking? and I'm just seeing the tail end, or is this something else.

The Bluegill and goldfish in the system are un-affected. The fish came from a tested regulated farm (tested the week of the shipment - no diseases).

Anyone ideas? Help.

[bunya boy]

Stop feeding.
With Nitrates that high, the fish are producing too much bio-load for your available GB space.
Get more Grow beds, plant more plants and don't feed for a few days. Do water changes but beware of quick fluctuations in temperature, pH and D.O., these will also be the demise of already stressed fish.

IanK

[nwestwood]

I stopped. More data. 4 more gone tonight. I did another 20-25% water change. There is a lot crude in that tank that is not ussually there(the water is clear, but this stuff settles to the bottom.), also floating is what I would call feces except it hangs together like a small worm would, but I'm sure it's not a worm. It might be pieces of intestine, it has a light casing on it.

Also, I have a larger particle fish food that I'm grinding to fines to feed. I ussually grind a couple of weeks worth and stick it in a zip lock bag in the greenhouse. Could this be spoiling in the heat? Should I be storing it in the refrigerator or freezer and pulling out just what I'm going to feed?

I have located another tank to cut a bed out of, and already have a space for it, and the plumbing is already in. I will get it added to the system, even so, I would not have thought a bunch of little fingerlings could cause such havoc. They are tiny fingerlings.

Anymore advice and guesses I welcome.

[bunya boy]

Hi NW,
Yes, they may be tiny but they still produce a load of nutrients. 130 to a 300gal tank (that already contained fish?) is a hell of a load IMHO.
I am only going to put 50 maximum into my 900 litre tank (about 300 gal) and I have 4x130 litre GBs, which will be cycling from a couple of months of continuous "Seasol" operation without fish. This is to allow sufficient bacteria to colonise the system before adding Fish. Plants will be producing in the mean time.
I think you have just gone too big with fish too quickly. If you are getting high Nitrate readings, it would indicate to me that your system is cycling correctly ( i.e. your Ammonia is being converted to Nitrites and Nitrites to Nitrates) it is just that you don't have sufficient Plant life to take care of the ammounts being produced. Nitrates in high levels can be just as destructive to Fish as high Ammonia and Nitrite levels.
I don't know what the solids are that are floating, but the floculating sediment could be anaerobic fish food that has rotted and clumped. This crud can drastically lower your DO levels, especially if combined with elevated temperatures.
If your floating stuff looks like intestine, then it probably is! Rot gut can be caused by anaerobic conditions, fetid food and high temps,; combining to produce almost septic growing conditions which will surely kill your fish.
The smaller the fish, the larger the consequence. Certainly refrigerate your food for storage, it will help keep it fresh. Other than that, up your GB area or keep less Fish.

Hope you get it sorted soon. I hate to hear of fish deaths.

Cheers IanK

[GaryD]

Hi,

I don't have the time to read through many posts right at the moment, so excuse me if I ask questions about your systems that I otherwise ought to know.

Are these fish in the same water column as your other fish (albeit in a different tank)?

What is the average daily ambient temperature - minimum/maximum?

How much water is in the tank that contains the dying fish?

Gary

[Ravnis]

I would suspect this from your description.

http://freshaquarium.about.com/cs/di...columnaris.htm

Notice that a treatment listed is salt which is the prescription of choice.

Salt causes certain types of bacteria cells to swell. THe fish cells can handle it; the bacteria's can't.

Melafix does wonders... but with it stating not for use for food fish, I would hesitate to recommend it. It is my opinion they just didn't want to hassle with food and drug testing. This is my opinion though and not based on any known fact.

[nwestwood]

Gary, Yes the fish are in the same tank with the Bluegill, daytime water temps were 74 (23c), night time 70(21c). the tank volume is 275-300 gallons (1000 litres) with about that much more in grow beds and DWC and sump tank.

Ravnis, I looked at the description for columnaris, it might be this, but it's not white spots or saddle back, in some it looks much more like they had a chunk of fuzzy mold 1-2mm on the front of their head.

I've done more research on Hybrid Striped Bass (HSB). Rebecca Nelson from Nelson and Pade in the book "Aquaponic Food Production" states: "The hybrid striped bass, ..., is not a good choice for aquaponics because they are reported to have a low tolerance for potassium, an element that is sometimes supplemented in aquaponics." Although HSB is a good choice for recurculating aquaculture where you don't supplement other minerals, it may not work in Aquaponics.

I do supplement potassium. I've done more searching and found several research articles on the subject and have emailed the authors for more information. HSB were not my first choice, but the only other warm water choice approved by the State. Maybe I'll have to stick with Bluegill until I can apply for an exception to the rules.

I lost more overnight, It hasn't changed yet. But still no problems with the older Bluegill and goldfish in the system. I stopped feeding completely yesterday. The water is clear (except redish from iron). I've been adding ice to keep the temperature down below 74 (23C). And doing partial water changes daily. The nitrates have dropped to the normal 10-20ppm. Dissolved Oxygen remains above 5.5 usually it tests 6-7.

I've frozen a few of the recent deaths and may send it to a lab to find out exactly what it is. But, HSB may not be a good choice for aquaponics.

[GaryD]

Hi,

Let's look at some of the factors involved in your situation:

• You're keeping HSB and they're not recommended for AP.
• HSB and potassium-sensitive and you're using potassium.
• You have several different breeds of fish in the same tank - this works in very rare situations - is likely to be causing stress to the smallest fish.
• You've got a disease of some type - further evidence of stress.
• You appear to have had quite high ammonia and nitrate levels - affected fish may have bright red gills.
• The fish are dying with their mouths wide open - suggests oxygen levels might be a problem. Your temperatures would aggravate any tendency toward low oxygen levels.

Any one (or a combination) of the above might be the explanation for your problem.

I'm a little surprised at the fact that you have elevated ammonia levels given the number of (what I presume to be) fingerlings in your tank (1100 plus litres). Do you have uneaten foot in your tank?

The nitrate levels (30ppm) are not an issue. Nitrate is nowhere near as toxic as ammonia or nitrite. Nitrate levels may be as high as 400ppm in some systems.

I'd boost oxygen levels immediately.....dose with salt......and stop feeding until your ammonia and nitrite levels recede.

Gary

[nwestwood]

Gary, There was a bunch of crud in the bottom of the tank a few days ago. It's cleared now. I didn't think I was over feeding, but if the bluegill stopped eating due to the introduction, then it's possible. It's clear now.

I have cucumbers, tomatoes and lettuce growing, will salt hurt any of these?

What type of salt is best? Will water softener salt be sufficient or do I need to buy aquarium salt to be safe?

[GaryD]

Hi

Gary, There was a bunch of crud in the bottom of the tank a few days ago.

Crud (whether it be uneaten food or fish wastes) will eventually become ammonia and will consume oxygen in the process. If your system was low on oxygen (and at your ambient temperatures it may have been borderline) the muck on the bottom would not have helped.

I have cucumbers, tomatoes and lettuce growing, will salt hurt any of these?

I'd be thinking of 1 or 2 parts per thousand - shouldn't be an issue for the plants.....and it will act as a tonic for the fish.

Use salt that has no additives.

Gary