Backyard Aquaponics
A place to discuss aquaponics

Yet another "my fish are dying" post.

After a whole week of battling death and despair about 1/3 of my 100 fish have died. They're mirror carp.

They have been in the system since last summer, well over 6 months.

I'm trying to write this in some kind of order, but there's too much I want to say to fit it properly in a short post. I feel I need to explain many things in order for you to get the picture, however as an easy way of feedback, here is the album http://imgur.com/a/RjMgd/all.

FEED
I have commercial fish feed, consisting of
Protein 40%
Fat 18%
Ash 9%
Fibre 3.5%
Phosphorous 0.8%
Vitamins A, D3, E.

It is not a feed for Carp, but it is the closest I've been able to get.
To avoid problems I've also been feeding the fish little amounts of bread, pasta. As well as Lemna (duckweed), earthworms and BSFL when available.
However the food has mostly been commercial feed because I haven't got the necessary production of natural feed yet.

TEMPERATURES
From November up until now it has been cold. For a couple of months water temperatures have been dropping (not every day) bellow 10 C, although only during the night, the days are still somewhat warm even in winter. Fish have been eating little, supposedly due to low temperatures.


WATER QUALITY
I've got an oxygenator, A 3000 litres fish tank with 100 (now 65-70) carps of a weight each of 10-40 grams, so definitely the problem is not with oxygenation. Besides it's winter and oxygen stays dissolved better, also the pump is running 24/7, adding to oxygenation.

pH 7-7.5
Ammonia 0
Nitrites 0
Nitrates 20-40

I started with a pH of 8.4, but during the past few months I managed to drop it, adding very little amounts of HCl every second day, up to a total of about 3-4 litres of HCl, at a 20%, could the addition of HCl in such a quantity cause a problem of poisoning?
I also had the usual spike of nitrites but it was resolved swiftly long ago.


FISH BEHAVIOUR AND SYMPTOMS
About 10 days ago some fish started to swim erratically, slow, not being able to maintain a correct swimming posture. Sometimes they go on "shock", stay immobile except for a minimal trembling and expected gill movement. Then they resume normal swimming after a few minutes up to an hour. Then they go on repeating this cycle throughout the day.

Some of them are showing popping or swollen eyes, like this one here. The eyes don't necessarily swell evenly, one can be bigger than the other.

As far as I know only one of them has shown red dots, typical of Aeronomas salmonicida infection, this one. However the symptom that is most common among all casualties is the red patch right bellow the eye can you can see in this fish.

This symptom has also been shown only by one fish. Very bloated, here

To summarise symptoms.
The most common one is the red patch right bellow the eye, being in most fish.
The second one is popping eyes, it's hard to tell the incidence of this symptom because a slight swelling I might not be able to recognise. I'd say 1/4 of fish show it clearly.
Then there are two fish that show symptoms no other fish do, one with the red dots and the other one being bloated.
Also I've seen some fish's shit being white/translucent, which is not a good sign I believe.

Another thing that worries me, could this "T" connector cause some type of bronze poisoning?


WHAT I'VE DONE SO FAR
Salted the tank to 3 grams of salt (no additives) per litre.
Been salt bathing the more weak fish on a container with a 15 grams per litre solution. If the fish was eak and stayed on top I'd have him bath for only 30 seconds, if the fish was comfortably swimming on the bottom I'd bath him for up to 15 minutes. Ive been doing that for the last 4 days, once a day.


So, what do you think guys is happening to my fish? And what should I do?

It's been hard to lower the pH of the water, really hard, so I don't feel to inclined to change all water again because I'd be on 8.4 again. I'd also be losing the beneficial bacterial colony as well as the nutrients for the plants (planting season now).

Sorry for the long post, I've tried to structurize it in some way although I fear I didn't succeed.

Bronze is primarily copper which is something you don't want in your system. That may be the cause of your problem. Also is that green hose made for potable water? regular garden hoses may leech chemicals into the water over time.

What kind of metal is the faucet attached to the T made of?

The fish definitely have dropsy. As to what is causing it, it could be anything.

The T-connector and tap may be the culprit and even if they aren't I'd be inclined to change them anyway, given one looks like it's galvanized (which leads to zinc poisoning) and the other bronze/brass (copper and/or zinc poisoning). And as per Tlrobb's suggestion, I think changing any hoses that aren't drinking water safe might be worth a try also. If they are what's causing it, water changes may help.

As for the fish themselves, by the time they have shown obvious signs of dropsy it's usually too late for them, so it might be kinder to euthanase the severely affected ones. If you can spot fish with any minor signs, I'd quarantine them and keep the water they are in aerated, salted and fresh. It's debatable whether antibiotics work, so I'd just quarantine first, and do some water changes in their main tank. I'd cull the really sick looking fish, chances are they won't recover.

Sorry, probably not overly helpful, the key really is finding what the cause of the problem is, and given how many possibilities there are it's hard to narrow down. I'd just do what you can and monitor the situation.

I really hope you can find a solution, good luck.

Thank you very much to everyone who's answered.



The hose is for potable water, I made sure of that.

The other two pieces, the T connector and the faucet are also for potable water... do you still think they can cause problems even if they're for potable water? Would a close pic of them be helpful?

Again, thanks for taking the time.

Potable means safe for humans but may not be for fish. No metal apart from stainless steel and maybe pure iron is good in fish water AFAIK

I am no vet or biologist but it looks like toxicity poisoning to me.

re-evaluate every component of your system, and anything that could drip into your system... if they lasted 6 months and then all died at once, it seems like it would be something that happened recently.

Thanks guys. So far half of the fish have died.

I got rid of the two metal pieces and I've been slowly changing the water since yesterday.

Can you describe the "oxygenator".

I'd get rid of the brass but it may not be the problem. Also the flexible hose looks like PVC and flexible PVC is not a good idea in AP.

This is my oxygenator (they're probably not called this way huh)


Which flexible hose are you talking about? The two transparent hoses that I use to pump air (transparent) or the ones I use with the water pump (green color)?

The green hoses are supposedly for potable water. The ones for the air I don't really know, should I worry about them?

Should I worry about the green ones even if they're for potable water?

Thanks for taking the time Stuart.

Flexible PVC is certified for potable water use but it does leach human hormone analoges into the environment or in this case your AP system. I was referring to the green hose but the clear tubes maybe PVC as well.

We would call that an air pump.

Are the airstones connected to the airpump just at the bottom of the tank or are they somewhere else?

There are two airstones that are connected to the clear tubes right at the bottom of the tank. There aren't any other airstones, why? Should I also be concerned about airstones?

I've just checked the hose, it doesn't say what's made of, it does have the word "atoxic" on it though, and as I said I bought it for potable use too. I'll ask at the place where I bought it if they know if it's made of PVC.

If it is made of PVC, what kind of hose would you recommend me to buy then?

Are we talking about the clear ones?

If so you can get silicone ones that are clear or otherwise use HDPE or LDPE (which are often cheaper anyway).

Some of the symptoms of your fish resemble gas bubble disease (popeye and burst capillaries). Since your airstones are just in the bottom of the tank this is very unlikely to be a part of the problem.

When you were talking about an "oxygenator" I wondered if you were using some sort of airlift or U-tube aerator but you are not so don't worry about it.

Instead worry about what is killing your fish secure in the knowledge that it is not Gas Bubble Disease

Alright, I asked the seller and the garden hose is made of silicone, for potable water, so I assume I'm fine there.

I changed the clear tube just in case, for a tube I bought in a pet/fish shop where they sell them for that specific purpose.


I have to say that since I changed the water, almost 2 days, no more fish have died. I'm becoming more and more optimistic I might have saved them. Although some of them still have popping eyes... I'm not sure what'll happen to them, whether they can get back to normal or they'll eventually die.

I still have to do a proper count but as an estimate half of the fish remain alive so far.

By the way your avatar is freaky