Backyard Aquaponics
A place to discuss aquaponics

True, some breeders may not be good and let their stock start turning out weak fish genetically. Didn't think of that along with shop care of the fish.

That seems highly unlikely to me as the fish have been fine for weeks then BAM! 10 dead in three days.

I moved them to a cooler with about 10 gallons of straight rain water and an air stone. I'll keep an eye on em for a couple days and see what happens.

Are you filtering the water in the cooler?

That's bamboo you have around the system, correct? I don't suppose it is coated with anything is it? Maybe, (if it is) the coating is draining down into the fish tank. Tests of water don't identify something not being tested for so it might be the fish are being poisoned by the coating...?

Howdy mate, one thing that hasn't been asked yet is what is the oxygen level. Do you have an air stone in the ft. I would have thought the supplementary air would be required with large stock levels.

That rain water collection what is the roof surface and is it coated, what are the gutters made of?
An Asphalt Shingle roof could certainly leach things that you might not want in your food supply and the asphalt shingles tend to also grab pollutants from the air and release them to the water if you collect water off them so I wouldn't really recommend that as a roof surface to collect rain water for use in an AP system. If it is a metal roof, what kind? Galvanized or GalvAlum or ZincAlum coated metal roofing could leach too much zinc into the rain water to be safe for the fish long term and fish dieing of zinc toxicity apparently tend to do it several months in and seemingly for no apparent reason. At least your rain tank isn't an old galvanized cory tank. From what I can see of your downspout I'm guessing the gutters are perhaps aluminum and those are generally primed on the inside so probably not the source of a problem.

What is your pH running now days? A high pH when using rain water seems a bit odd, are you using something to add minerals and bring up the hardness of your rain water or is there just that much limestone dust getting into your system to keep the pH high? What is your media?

Putting the fish into a separate cooler with with rain water and just an air stone probably isn't gonna save them.

As to the system and is it cycled or not. I'll venture that it probably is since it kinda sounds like perhaps you were testing every day. You said there were maybe lots of plants and the nitrite did spike. When it's time for the nitrite to fall, it can sometimes go from quite high to a trace or near 0 in like a day. Often the pH falls about the same time if there is not much carbonate hardness in the system at that time, if there is a lot of carbonate hardness in the water from either hard tap water or from media with limestone in it, then the pH may remain high.

The reason your plants are not doing as well as you had hoped probably has to do with 1-the high pH, most plants would like the pH below 7 to get the best access to the whole spectrum of nutrients, and 2-a water temperature of 90 F is warmer than most plants like to have at their roots. In a Hot summer area like that I would recommend expanding to a larger fish tank if possible, putting up some shade cloth, and perhaps even sinking the fish tank into the ground a bit to take advantage of the thermal mass of the earth. I'm in central FL and my systems that have in ground tanks of around 300 gallons have far more stable water temperatures than systems of the same size with the tank up on top of the ground. And some shade cloth (like 40% aluminet) would help this time of year. Doesn't block much light but does greatly reduce the temperatures under it in the summer and provides diffuse light and it can even be left up in the winter to help reflect radiant heat back down to the plants on the freeze nights.

It's warmer than most fish would like also.... you need to look at ways to insulate/cool your system...

I doubt it is temp-related. The fish have suddenly started to die. That's why I wondered about the surrounds of the GB/FT. A coating would be fine for a while but then start to leach out.

My goldfish survived a Bendigo summer just fine - 30º+ was fairly common and in direct sunlight so I don't think that is going to be causative.

I'd be looking for what changed and maybe finding out what is on that bamboo - they tend to coat that stuff to help it stand up to weather.

Are you saying 32º C water temp is ok for the fish!

Sounds pretty warm to me.

Who... moi.... nope I'm saying...

"It's warmer than most fish would like"

And that.... "you need to look at ways to insulate/cool your system"

The fish deaths could very well be temperature related.... water too hot... and DO too low... or both stressors combined over a period of time...

As Rupe Says.

90F water might be survivable for warm water fish but it is very warm and probably not much dissolved oxygen to go around so if there is not a really good constant supply of dissolved oxygen being pumped into the water at that temperature it doesn't take long for the dissolved oxygen to run out if say there is any algae growing in the water, overnight the fish could suffocate. And such situations don't always mean all the fish die at once but you might notice if the fish are gasping at the surface at dawn that it could be a real problem for them.

I've had a whole tank full of fish die because of an over night power fail during warm weather when I didn't have battery backup aeration going. If there is no supplemental aeration and the system is running on a timer or even just a single bell siphon it could be possible that overnight the fish are struggling for air between cycles and the weaker ones are dropping off. At least that is my first guess when people tell me the water is that warm and the fish are dieing but have no marks on them and water quality is otherwise fine.

Sorry been away for a bit. Thanks for all the great comments. Let me address them in order.

1) I changed the water twice while the fish were in the cooler. I did lose a couple fish in the cooler at first but then went a couple days with no dead fish, so I returned them to the main tank. I have had two dead fish since.

2) The Bamboo is coated in polyurethane I believe however it has been on there for a while and doesn't come in contact with the water. Only in the case of rain could any runoff reach the fish tank. I'm dubious that it has any bearing on the situation.

3) The oxygen level in the tank... I am running two air lines one to a stone that is about 14 inches long and a second to a regular stone. The single bell syphon cycles about every 13 minutes around the clock. It dumps directly into the tank and makes a lot of bubbles.

4) The rain barrels collect the runoff via aluminum gutters from a composite roof. (asphalt shingle) Perhaps that is my best candidate for the cause but the effects again appeared somewhat suddenly. if a poison was to blame it seems likely I would have come out to find all the fish dead in the space of a few days not one or two a day, for a couple weeks.

5) PH is running between 7.4 and 7.6 lately

6) My grow media is pea gravel. I don't see any limestone in it however.

7) The water temp has been nearly the same for a while, and in any case hasn't experienced any sudden changes.

I reduced the plant load a little. I had a couple viney type plants that were inappropriate for the grow bed and my thought was why rob nutrients from the plants that need it more. I can't say that it has had an appreciable effect yet.

9) Ammonia >0 <.25, Nitrites 0, Nitrates >0 <5.0

10) I'm down to about 17 two inch and under size, common goldfish, in 305lt. They seem to have a ravenous appetite and are not gasping for air.

Thank you all so much for your help. I probably should get some soil and pots for the few herbs that I really want to grow and be done with it.

As for the rain water collected off asphault shingles. If the fish were dieing because a neighbor sprayed with some nasty chemicals and the rain washed that into your tank then I would say yes expect to see sudden death of many fish.
However, if it is something less acute but still toxic coming off the roof, then no I would not necessarily equate slow sporadic deaths to that NOT being the problem. People dealing with zinc or other metal toxicity often don't seed sudden death but rather just have the issue with not being able to keep fish alive beyond about 4 months and others might keep fish alive longer but have fish heath issues that they can't explain without getting detailed lab water analysis done.

I know of one guy who changed out media, sterilized and re-filled a system several times thinking it was disease problems killing his fish before he finally gave in and lined his galvanized stock tanks.

Another guy had issues with the Nickle leaching from the old chipped bathtubs he was using. Metals and fish are a bad combination. Who knows what might be hidden in the composite shingle materials.

Maybe I'll try switching to tap water that has gassed off the chlorine and see how that works.

Haven't lost a fish in a couple days... fingers crossed!