Tilapia trouble

[tom landschoot]

Hello All!

I have had issues with my tilapia over the past 2-3 months.

They just keep dying. They look healthy and the next day yet an other one is dead.

Even one of the dead ones was holding a full mouth of eggs.

Every time I notice a fish in trouble, I take it out and put in a big fish tank. So far, they always recover - even after being upside down for an agonizing 3 days.

The water in the system is nearly perfect (amonia 0.25 ppm, nitrite 0 ppm,nitrate 5.0 ppm, strong airation, temp between 78 and 84) and I am getting tons of vegetables. I have 4 bell syphon grow beds filled with (the expensive) hydroton and clay pepples that has been running for 2 years. They ph is 8, due to the hard water and strong evaporation in Tempe, AZ.

Something must be really wrong with the system - once put in an aquarium the sick fish always recovers.  My fish tanks are now getting crowded and my aquaponics empty...

Do any of you have advice?  Thanks so much!

Tom

[Glenn]

Sudden infrequent  and unexplainable fish death is often a real puzzler.

One thing, I think should be considered is electrocution. It might seem odd but actually fish in captivity are subjected to electrical faults more often than we might realize. I have seem systems that look like the cord/cables were salvaged off of a construction site in the dead of night or winter.

Normally, we trust that our systems are protected by our home electrical breakers/distribution panel and ground fault receptacles (GFCI) But when we add heaters or additional circuits, or forget that cords laying in the sun and weather deteriorate, we might over look the danger that tiny faults aided by small amounts of moisture can kill..

Just something to think about. I hope you determine the cause of your fish deaths soon and can continue to turn out tons of vegetables and fish.

[tom landschoot]

Thanks for your advice, Glenn.

Is there a way of testing this?  Or should I just get a new pump and see if there would be a difference?

The airpump is not touching the water, so it would only be the water pump.  

The electrical cord looks fine, but the pump has been running for a long time.

Tom

[Glenn]

Yes Tom, there are tests that can be performed to determine the safety of electrical pumps and apparatus like extension cords and conductors. Most service manuals advise the basics. Or a small appliance and electrical repair shop or electrician could help advise or do the tests for you.

If you can rig an air pump as an "air lift" pump for a time, you could take your water pump off and judge the likelihood that no more similar deaths occur for yourself. Or indeed replace the pump if you have any doubt to it's safe and shock free operation.

One problem that often comes up during the testing of industrial electrical apparatus is. the destructive nature of the tests themselves can contribute to future faults. But again there are some simple less destructive tests and checks.

Oh, and don't forget that any piping and metal structure components CAN conduct stray currents including lightning and any other surge near by. Submersible pumps are hermetically sealed to prevent this sort of fault as well as can be expected within the warranty. 

tom landschoot said:

Thanks for your advice, Glenn.

Is there a way of testing this?  Or should I just get a new pump and see if there would be a difference?

The airpump is not touching the water, so it would only be the water pump.  

The electrical cord looks fine, but the pump has been running for a long time.

Tom

[Jim Joy]

You can buy grounding rods for aquariums to stop stray voltage.  Salt water aquarium folks almost always use grounding rods in the tank.  This is what I have in my outdoor aquaponics fish tank:   http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=3946

Another possible issue is oxygen content.  You can't over do bubblers and sprayers during the summer.   Weaker fish will die first.