Dead Barramundi

[DaveOponic]

My Barramundi were doing so well until I came home today to find most of them dead ... 27 dead Barra and about 15 that have survived.

They were healthy and active last night and I may have overfed them as they were slapping around at the surface more greedily than ever.

This afternoon the water was fairly murky. No apparrent interuption to power supply and pump and aerator still working fine.

From their appearance, it looks as though they were gasping for air, so i probably need to provide more aeration and more filtration for the 1000 litre tank.

No signs of any other disease. Just sudden death or overnight asphixiation.

The Tilapia in the same tank are still healthy. No signs of stress or odd swimming patterns.

Are Barramundi more susceptible to dirty water or low oxygen? Nothing I have read so far made me think they were a sensitive fish. I will have to rethink their accomodation and give them a cleaner environment.

I am a bit devastated as this is the first major loss of fish in nearly two years of Aquaponics. I have only lost fish before one at a time, so was surprised to find so many dead.

The fish appear clean and healthy (see photo) and no signs of any other sickness.


Dave

[GaryD]

Hey Dave,

Bad luck mate! No-one who raises fish could help but empathise with the way you feel.

My guess, for what it's worth is that oxygen levels have dropped too low. The fact that the Barramundi have died while the Tilapia have survived seems to confirm this. My belief that it's low DO levels is further confirmed by the speed with which it's happened. Ammonia toxicity will kill fish in similar circumstances (gasping at the surface) but it's usually a more protracted affair.

One of the strengths of Tilapia is that they will tolerate indifferent water quality........but Barramundi are not the same.

The one thing we should take from situations like yours is that oxygen is essential.........for the fish, plants and bacteria.

The best advice I can provide is for you to get back on your bike, invest in some more air.....and find some more fish.

Gary

[Castaway]

This afternoon the water was fairly murky.

Sorry to hear about your loss Dave. I'm inclined to think that you may have over fed them too, especially if the water suddenly blooms into a murky cloudy mess. Water Quality is very important for Barramundi. (Maybe less so for Tilapia) Get some more fish and resist the temptation to over-feed the new batch. Thanks for sharing the bad news. We all learn from one another's experiences.

[Crusty]

Did you test the water at all?

My Barramundi were doing so well until I came home today to find most of them dead ... 27 dead Barra and about 15 that have survived.

They were healthy and active last night and I may have overfed them as they were slapping around at the surface more greedily than ever.

This afternoon the water was fairly murky. No apparrent interuption to power supply and pump and aerator still working fine.

From their appearance, it looks as though they were gasping for air, so i probably need to provide more aeration and more filtration for the 1000 litre tank.

No signs of any other disease. Just sudden death or overnight asphixiation.

The Tilapia in the same tank are still healthy. No signs of stress or odd swimming patterns.

Are Barramundi more susceptible to dirty water or low oxygen? Nothing I have read so far made me think they were a sensitive fish. I will have to rethink their accomodation and give them a cleaner environment.

I am a bit devastated as this is the first major loss of fish in nearly two years of Aquaponics. I have only lost fish before one at a time, so was surprised to find so many dead.

The fish appear clean and healthy (see photo) and no signs of any other sickness.


Dave

[DaveOponic]

Crusty, no I didn't test the water. It was a case of saving the survivors so I emptied the tank and siphoned out the poo and pellets on the bottom. I then quickly removed dead fish and re-filled the tank and further siphoned and vacuumed and tried to make the water as clean as possible to reduce risk of bacteria taking over and killing the survivors.

I also installed a powerful pump to create a swirling current. This has maintained a very clean tank for 24 hours. Today I have invested in a pond sized air pump with 12 outlets for airstones and have 4 stones in the tank tonight to provide good aeration.

The water is looking cleaner than it has ever been. Tilapia seem to be enjoying surfing the current while the surviving Barramundi have found the corner near the pump where they can rest.

The water is so full of tiny bubbles that I am sure there is not only enough oxygen for the fish but that it will have a beneficial effect on the plants as well.

If all goes well this week, I will re-stock with some more Barramundi.

Just wish I had have installed the stronger pumps before putting the Barra in the tank.

A swirling current in the tank makes a huge difference to the removal of solid wastes. Are there any down sides? E.g. is it possible that fish can get tired by swimming in the current all day?


Dave

[anniefish]

Hi Dave,

What a shame, but thank you for sharing, I'm sure it will help others down the track.

We had a close call yesterday, a couple of heifers got into the tank area and munched on the silver beet in the grow beds, they managed to block the drain hose and the bed was overflowing. Lost a bit of water before finding out. It's a horrible feeling to think we could have lost our babies.

Annie

[Crusty]

Sounds like you have it all in hand. Just watch you are not boiling the water too much. You will find with air stones that if you slow down the amount of air running through them, they will create smaller bubbles making the diffusion more efficient at either gassing off CO2 or O2. Mountains of turbulence from the bubbles does not mean there is more oxygen.

In answer to your last question, the fish do not necessarily get tired, however they do waste more energy fighting a strong current and will not put on weight and it will stress them.

Crusty, no I didn't test the water. It was a case of saving the survivors so I emptied the tank and siphoned out the poo and pellets on the bottom. I then quickly removed dead fish and re-filled the tank and further siphoned and vacuumed and tried to make the water as clean as possible to reduce risk of bacteria taking over and killing the survivors.

I also installed a powerful pump to create a swirling current. This has maintained a very clean tank for 24 hours. Today I have invested in a pond sized air pump with 12 outlets for airstones and have 4 stones in the tank tonight to provide good aeration.

The water is looking cleaner than it has ever been. Tilapia seem to be enjoying surfing the current while the surviving Barramundi have found the corner near the pump where they can rest.

The water is so full of tiny bubbles that I am sure there is not only enough oxygen for the fish but that it will have a beneficial effect on the plants as well.

If all goes well this week, I will re-stock with some more Barramundi.

Just wish I had have installed the stronger pumps before putting the Barra in the tank.

A swirling current in the tank makes a huge difference to the removal of solid wastes. Are there any down sides? E.g. is it possible that fish can get tired by swimming in the current all day?


Dave

[DaveOponic]

Sounds like you have it all in hand. Just watch you are not boiling the water too much. You will find with air stones that if you slow down the amount of air running through them, they will create smaller bubbles making the diffusion more efficient at either gassing off CO2 or O2. Mountains of turbulence from the bubbles does not mean there is more oxygen.

In answer to your last question, the fish do not necessarily get tired, however they do waste more energy fighting a strong current and will not put on weight and it will stress them.

Thanks for the info. I assumed more bubbles is better and the power of this air pump really went to my head until I read the instructions. I have 4 stones in the water (1000litres) and the swirling pump is sucking in lots of bubbles and diffusing them.

When i read the instructions for the air pump it says to let some air bleed off if you are not using all 12 available valves, so I did that and looks like what you said, smaller bubbles, less turbulence.

The fish seem to be having a ball, enjoying playing in the current and I think the corners provide enough quiet areas where some of them rest. The baby barra seem to hang around out of the strong current.

[Crusty]

One of your cheapest and easiest medicines is oxygen. Watch the water pump is not sucking any of the air or it will cavitate which will destroy the impeller.

Are the fish back to normal feeding behavior?

Thanks for the info. I assumed more bubbles is better and the power of this air pump really went to my head until I read the instructions. I have 4 stones in the water (1000litres) and the swirling pump is sucking in lots of bubbles and diffusing them.

When i read the instructions for the air pump it says to let some air bleed off if you are not using all 12 available valves, so I did that and looks like what you said, smaller bubbles, less turbulence.

The fish seem to be having a ball, enjoying playing in the current and I think the corners provide enough quiet areas where some of them rest. The baby barra seem to hang around out of the strong current.

[DaveOponic]

One of your cheapest and easiest medicines is oxygen. Watch the water pump is not sucking any of the air or it will cavitate which will destroy the impeller.

Are the fish back to normal feeding behavior?

Thanks again for the tip. I had never heard of cavitation. After reading about it just now on Wikipedia I am going out to the tank to move the air stone that is sitting directly next to the intake of the pump that is shooting millions of bubbles into the tank. It has a plastic/nylon impeller .... is that likely to be destroyed by the bubbles?

The fish are feeding nicely. The pellets end up in the centre of the tank where there is a dead spot in the currents.

Dave