Help! Our fish died!

[Lillian beretta]

We have a new system that has been functioning and testing perfectly. We added the talapia 100 (2 tanks 250lbs each 50 fish each ) they were doing well for about a week. My husband was testing the system daily. Ph was perfect, ammonia perfect nitrates were at zero however and he was afraid the plants might be getting yellow ( not really noticeable yet), so he added 1 cup of organic kelp fertilizer. The next morning all the fish were dead. Not one survivor. Did all the water testing again. All the levels were in the perfect range. ( the plants are still looking great). We waited 3 days then added 6 goldfish. It has now been 3 days and this morning one of the fish was dead. It has been total
One week since the death of the fish and we are not sure
If it is safe to add more. We are afraid the plants will not survive if we do not do something soon. Please advise.
:D

[Harold Sukhbir]

Hi Lillian,

Sorry to hear about your loss. Can you tell us about your system design( pump size,fish/bed ratios etc), and also the name of the fertilizer you used? Some pictures, if possible, can help.

[Keith Rowan]

i'd suspect the fertilizer.. was your system cycled before adding the fish?

[Lillian beretta]

Aquaponics

The pump size is 4,000 gallons per hour. We have a continuous, automatic, recycling water system. The system is housed in a heated greenhouse. We have 5 beds that are 75 gallons each. The sixth bed is full of duckweed. This bed does not flood and drain. It is constantly flooded. The others flood and drain. There is a 200 gallon sump. The water temp is heated and is reading at 75.6. The ph is at 7.64, the ammonia is at .25, the nitrate is 0, the nitrite is 0. The fertilizer was from kelp for less the product description is soluble kelp fertilizer. We currently have since the debacle snails and goldfish. Started with 8 goldfish and are down to 6. The snails are all fine. Water looks clear and smells great. Plants look great too. The dead fish look perfect. The oxygen is at 8.25 ppm. Do you think it is safe to add more talapia? We don't know what we can measure or change to ensure water safety other than what we have done.

[Lillian beretta]

The water was cycled before we added the fish and was actually growing plants. Please check the picture uploaded called Lillian's system.

[Harold Sukhbir]

Hi Lillian,

I think it seems obvious that the culprit was somehow the Kelp product. Fish are very susceptible to minute change in the natural environment, so we try to make small and gradual changes always. Could be just a bad batch of product, or too much quantity too soon, whatever the case, its still in the system water. If you bring new fish into this environment they may experience shock all over again. For me, i would do a complete water change-out and then recycle. If you can manage, drain the system and add dechlorinated water and ammonia, with some bacteria still in the moist beds and plant roots, you'll cycle fairly quickly, and be up and running in no time.

[Harold Sukhbir]

Hi Lillian,

I looked up the site for the kelp product, but there is very little information available. These products offer great benefits when targeting plants and are organic by nature so are great for AP being a natural ecosystem in itself, but because of the freshwater fish in the system we have to be cautious with the levels of application. What are good for plants may not translate well for fish. These products may not necessarily help with yellowing of plants though. Adjusting the PH lower, closer to a range around 6 to allow for better absorption of iron. To treat plant in the system we don't necessarily have to dose our water column. Also you can foliar spray iron-chelate (at night/with a wetting agent).

You don't have to throw away the kelp powder, used as a foliar spray your plants will love it. With most of these products, the dose on the package is prescribed for soil application, so to be safe, we should apply directly to the plants and avoid the risk it may pose to the fish.