Rate of death of fish

Hello, again.

About 2 weeks ago, I placed 2 pounds of gold fish in my 300-gallon tank. The water had been flowing through my grow bed for a few weeks before I added the fish (doing my water tests, then adding the gravel, etc), so there wasn't any chlorine or other city-added chemicals in the water at that point.

The temperature has averaged about 75 degrees.

After 4 days, I started having an algae problem, but had not, at that point covered the tank to protect it from sunlight. I put a tarp over the tank, and the algae pretty much has disappeared, though my water is still cloudy (partly from the gravel - I washed it off, but didn't get it completely dirt-free). The water that flows out of the grow bed and out of the spray bar (into the fish tank) looks clear.

I haven't quite figured out how much to feed the goldfish - I think, perhaps I fed too much. I ended up with 4 dead goldfish the other day. Not really thinking, I added ten 8-inch catfish to the tank yesterday, and this morning was greeted by 2 more dead goldfish and 2 dead catfish. I think I recall the girl at the hatchery telling me that too much left-over food can increase the ammonia levels in the tank. The aquarium water test strips I bought do not read ammonia levels; the pH is fine, the nitrites/nitrates are high, and the alkalinity was "ideal".

The amount of fish in the tank are not excessive for the size of the tank, so I didn't think they would produce enough ammonia, yet, to be problematic.

I have a spray bar to bring the water back into the fish tank, and the pump has, on multiple occasions "sucked air" when the timing of the drain cycle and pump time got messed up, so I feel pretty confident that the water was being aerated enough.

Any suggestions on what I might be doing wrong that some fish have died in the last couple days? How do I get the nitrites/nitrates lowered?

Thanks!

Here's a chart showing toxicity of ammonia based on temp & pH:


High nitrates don't matter too much but high nitrites are toxic. Sea salt can help mitigate. There's a ratio I don't have handy but I can look up.

Don't feed at all till ammonia is 0.

Nancie Baker wrote:The aquarium water test strips I bought do not read ammonia levels; the pH is fine, the nitrites/nitrates are high, and the alkalinity was "ideal".

Don't use the strips. Buy the kind in the squeeze bottles.

Thanks, Cj. I'll go out and see if I can still get one of those test kits this evening.

Got the kit; looks like my ammonia level is almost a 4.0 (goes from 2.0 to 4.0; the color is darker than a 2 but not quite as dark as 4), so I guess the fish have to live off the fat of the land for a few days.

How long, in your experience) does it take for the ammonia level to reduce to zero?

It'll take several days, at least. Don't worry, they wont starve. Check it everyday. I like to document that kind of thing on a spreadsheet to see the improvements.

Goldfish are quite hardy once they are adapted to their environment but that'll take time too.

Thanks. The gold fish seem to be okay for now - vigorously swimming about. But the other 8 catfish died. Guess the shock of being dumped in that much ammonia was too much. Luckily, they didn't cost me much. I will for sure wait till the level is zero before I replace them!

First, stop feeding your fish. They can go for weeks without food.

It sounds like your system is not quite cycling yet. I had this same problem last year when I introduced bluegill fry to my few weeks old tank. I lost about half ( 8 ) before things finally adjusted. It took about a month. Google cycling aquaponic systems if you don't know what I mean by cycling.
Sylvia Bernsteins aquaponics book is a great overview for the new user, and there is a lot of info at her store at aquaponicssource.com.

Have you introduced any pond or aquarium water to your tank? That is one way to inoculate your water with the proper bacteria.

You can also try to fix the nitrites by adding salt, I forget how much per gallon, but the info is out there.
There are several good aquaponics forums on the web where you should be able to find lots more information.
Good luck!

Thanks, Dan. I've been looking into this on YouTube and other places on line. I know my problem was with over-feeding and I feel guilty if I don't feed. I let them go 2 days without food, then, last night gave a small bit, and will hold off feeding again until I have things under control.

I'm trying to do a partial water exchange, but, because of the size of my tank (300 gallons) and the way I have things arranged in my greenhouse, this is going to be a slow process, taking several days. I am considering some type of chemical adjustment, but I will consult with the fish hatchery where I got my fish before doing that.

I do have pond water available, and had considered adding some, but wasn't sure if that would help or not. I have been using rainwater for replacing evaporative loss, and with the exchange, I have a 100-gallon tub that I'm filling with tap water and letting sit for a day or two before adding any of that. (Not exchanging more than about 50-70 gallons at a time because of my set-up).

I will look up the salt again - I saw it once, but didn't pay enough attention to that at the time.

Thank you for your reply and advice!

This may sound odd but here goes. I was reading about raising minnows and the article talked about ammonia. It said ammonia had to be introduced beforehand to kickstart (bacteria?enzyme?) that would eat it. It's a brown scum layer that coats over volcano rocks or other filter media.

One plus one equals two ....so....I looked left...looked right....then peed in the tank.

I added the minnows a couple weeks later. All is well.

Just don't tell anybody....

LOL Thanks for that Wayne! I went a bit backwards on my set up...I had some plants already in the grow beds (minus any chemicals that one might use in hydroponics), hoping that somehow, they would introduce bacteria into the grow media while I cycled the water and awaited my fish.

Then, because my tank is 300 gallons, and I only got 2 pounds of gold fish (maybe 20-30 at about 3-4 inches each), I figured it was okay to feed them a bit extra, hoping to get that initial boost in ammonia. I then forgot to protect the tank from the sun and started getting green algae pretty thick. By the time I got that taken care of, I had elevated nitrites/nitrates (but didn't have a test kit that included ammonia - just some test strips), so didn't equate those with high ammonia levels. Then I go and eagerly add 10 catfish, hoping they will help keep the algae down, but the ammonia was too high and killed them within the first day.

<sigh> I was so worried about the plumbing and the plants, that I didn't study up enough on the fish. I didn't realize changes could occur so rapidly on their end. At least the goldfish (and the catfish) were not very expensive. Live and learn!

Don't forget - pure sea salt.

Also, if it makes you feel better, people say you need to kill at least 1000 fish before you know what you're doing! 990 to go...

Thanks, Cj.

I had a brief stint as a disc jockey - six months. (Midlife crisis thing). Anyway, I was told that you're not really in the business till you get fired. At least, when I did, it was because the station was sold and the new owner got rid of everyone!

I will look into the salt.

I found the ratio: 1 gram sea salt to 1 L water.

If Nitrites creep up to 1, salt to 1ppt to mitigate the nitrites - that's 1kg of salt (sea salt) to 1000L.... (1 gram to 1 L) i.e. 75 g for 20 gallons

Thanks, Cj.

The little bit of water I was able to exchange yesterday didn't do anything to reduce the ammonia level, so I will try some sea salt.

Cj Verde wrote:Here's a chart showing toxicity of ammonia based on temp & pH:

High nitrates don't matter too much but high nitrites are toxic. Sea salt can help mitigate. There's a ratio I don't have handy but I can look up.

Don't feed at all till ammonia is 0.

^^ I use this one too. great resource. I'd like to know more about the sea salt ratio though, if you can find it.

I stopped by the fish hatchery where I bought my fish and they sold me a product that is considered a "rapid ammonia and nitrite reducer". I will give this a try first, since I don't have the quantity of sea salt on hand that I would need, based on Cj's post (I would need about 4-5 CUPS of sea salt for my 300-gallon tank).

Also, the sea salt doesn't get rid of the ammonia, it just prevent fish problems if the nitrites are too high & may help if the fish are ill for other reasons.

If the ammonia is too high, the nitrites will be too but there is a time lag. Did you test nitrites too? If not, pick up one of those tests. You get to feel like a mad scientist shaking up the vials & whatnot.

You want ammonia & nitrites at 0 but it's common for ammonia to hang out at the .25 level which is fine & often means the test is a little old.

Yes, the nitrites were high, too, though that is just with the dip stick. What I see, seem to be active and otherwise okay. Not sure I'd know what an "ill" fish looked like.

In regards to adding ammonia before hand?

Totally works, but you have to do it in a certain way. Admittedly, when I did this, it was ten years ago, and I did it with a 60 gallon tank based off of some notes by a biologist at UC Davis that I found on some random website. No way in the world I'm finding that again. But it worked beautifully, I had not one fish die, or even look stressed. So I'll share what I recall about what I did.

Basically, the idea is to add something with bacteria already on it, like substances from another working pond (pebbles, lava rock, something that's kept wet so the bacteria are still alive, obviously).


What to do:
After adding the pebbles or whatnot from another tank, you want to add the ammonia. NOTE: The cheapest ammonia is typically what you want to look for, because nowadays, ammonia is often 'ammonia plus soap,' but the cheaper varieties are often still just plain ammonia.

Start off with a small amount (I'm not sure what would be a small amount for a 300 gallon tank, honestly...more on that in a sec). Test for ammonia levels 24 hours later. If it is not zero, then keep testing every 24 hours until ammonia is zero. When that happens, add the same ammonia as you did initially and go through the testing regimen again. When ammonia levels drop to 0 within 24 hours, that means the bacterial population has grown to a large enough size to eliminate that amount of ammonia.

At that point, you increase the added ammonia and go through the entire thing again. The goal is to estimate how much ammonia your fish will produce in 24 hours and get it so you have grown a bacterial population that will consume that amount in 24 hours. If you end up putting in less fish at first but want to keep a higher bacterial colony going, you have to continue adding ammonia (and yeah, pee would work, from what I've heard...have to check what the ammonia concentration would be, though, LOL), or the bacteria levels will drop to match the available ammonia levels.

This site has a little sidebar for how to calculate out ammonia output levels for koi or goldfish: http://www.fishchannel.com/setups/ponds/pondkeepers-guide-to-filtration-2.aspx
I'd guess that you could estimate what a 'small' amount of ammonia is for your tank based on what the end output will be with the fish you'll be adding, maybe take a 1/4 of that or so, perhaps?
With my 60 gallon tank, I believe it took me 2 weeks to get the bacteria colonies up to the level I needed, but honestly, it's been so long I could be really off on that one.

Hi Shauna; thanks for the info. I'm happy to say the product my pond mgt place sold me did a great job on lowering my algae level. After offering some food, the level almost went to 0.25, but skipping a day's feeding let the level drop back to zero. I most certainly was over-feeding, but my grow bed is well established now, the fish tank water is very clear, and the fish seem to be quite vigorous and healthy now. Hopefully I won't have to try and adjust too much when I add catfish down the road (the pond mgt place was out of them; oh, and they had their own troubles with that batch of catfish, so said it may not have been all my fault they all died within 24 hours of putting them in my tank!).

I love this thread! You're jumping in with both feet, which is a great way to learn.

Have you gotten the ammonia under control yet?

I remember being surprised how much salt my system needed too. Like a pint.

The ammonia is no longer a problem, and neither are the nitrate/nitrite levels. The pH is around 7.6, which apparently is good for gold fish. I tried to add another dozen catfish to the tank, but over the course of about 3 weeks, they, too all died. The hatchery where I got them say they have trouble keeping the catfish in their tanks, so it's possible it was a problem with the fish and not my system, but, I am not going to worry about it any more this year. Our weather is starting to cool down, and the hatchery won't get any other breeds of food-fish in till spring, so the goldfish will have to be it for now.

I have an immersible heater for the winter, and am starting some seedlings to see how well I can keep up the green house, but this is all still an experiment for me, so I'm not going to get disappointed if things don't survive until spring. I need to get some wrap to help insulate the green house, and I have a small electric heater I can put in there, too.

Wish me luck!

Cool - great attitude! I'd discourage you from using your electric space heater. Done that. It'll cost a lot to heat your greenhouse.

Have you insulated and air sealed your grow beds and fish tanks, and insulated your piping?

Not yet, but I've got plans to.