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Oh the humanity! 40 Rainbow Trout dead in less than 24 hours....

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Yesterday I purchased 40 3 1/2 inch Rainbow Trout. They had an hour long trip back home at which point I put them in my IBC based 400 gallon system. At this point they all seemed to be alive and happy. The tank has 4 air stones attached to an air pump. In less than 24 hours they were all dead. They died off as the day went on, a couple in the morning, more in the afternoon, and by night they were all dead.

Water Parameters:

Temp: Around 55-60 degrees (breeder kept them at 50).

PH: 6.5

Nitrate: 0

Nitrite: 0

Ammonia: 0

Additional details:

The tank did have a good deal of algae in it which they seemed to prefer over the pellet food. I do not have a meter for dissolved Oxygen. Aside from the algae the water is pretty clean, no obvious contaminants other than a bit of clay dust on the bottom of the tank from the clay pellets.

I did do a partial water change which seems to not have much of an effect.

Conclusions:

My best guess is an Oxygen problem. Some of them appeared to be popping up to the surface of the water to gasp for air but not all of them. The under water pumps blast water into the tanks pretty fast.

The pump in my tank is pretty over powered and could have had something to do it maybe?

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It should also be noted that last year I raised 10 Blue Gills in the same set up. Nothing has changed.

I have some small veggies in the beds. Greens, Tomatoes, and strawberries.

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I dont have experience with trout but with other fish  i find these types of deaths are usually the damage was done in transit and it just takes a couple of days to show up.  Do you know what the PH was of the water they came from? Just speaking hypothetically if the hatchery  water  was 7.5 you would need to bring them down to 6.5 over a couple of days.  Also, if ammonia was high in transit it could kill them days later.. low do.. all the normal things that can kill fish if they happen during transit can still cause a delayed death.

 

I handle a notoriously fragile fish when i handle crappie. I make sure to transport them in the dark. If the hatchery puts them in a clear bag, i put the bag in something like a cooler and if i cant close the lid i also put a towel over it. I find it helps a lot.

 

 

Also, i thought you werent supposed to feed trout 24 hours after a big move like that? maybe i am wrong.

 

brian

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I don't think it was an oxygen transport issue. You would have already seen some issues in the coolers.

It's something in your system.

When did you check ammonia and nitrites? Could your nitrates be excessively high? Trout have issues with high nitrates unlike bluegills.

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I tested nitrates when I put them in the system, this morning, this afternoon, and just now. It tested zero every time.

If your nitrates are zero how are you growing any plants?

Even with plants, if your system is cycling you should be reading nitrates.

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@Cecil

I don't really think it was cycling at this point. Like I said it was less than 24 hours.

@RupertofOZ

vege boxes? Yes they were Styrofoam.

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They all tested zero all the way through. I don't doubt that it would have cycled at one point but I'm trying to figure out why they all died. Unless they spiked and vapidly diminished in between the 3 tests in less than 24 hours. It just doesn't seem very likely.

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I don't think it was an oxygen transport issue. You would have already seen some issues in the coolers.

 

Not necessarily.....

 

An hour to transport a very oxygen dependent fish such as trout could very well have meant they were oxygen deprived...

 

And unless checked frequently during the journey... quite possibly gone unobserved...

 

It's not uncommon for oxygen deprived fingerlings to keel over during the next 24 hours after being introduced into the tank...

 

As most of the damage during transport is internal... resulting in brain and liver damage....

 

Fingerlings should always be transported bagged with oxygenated water.... or in a properrly oxygenated transport tank...

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Not necessarily.....

 

An hour to transport a very oxygen dependent fish such as trout could very well have meant they were oxygen deprived...

 

And unless checked frequently during the journey... quite possibly gone unobserved...

 

It's not uncommon for oxygen deprived fingerlings to keel over during the next 24 hours after being introduced into the tank...

 

As most of the damage during transport is internal... resulting in brain and liver damage....

 

Fingerlings should always be transported bagged with oxygenated water.... or in a properrly oxygenated transport tank...

I think you're probably right.

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They all tested zero all the way through. I don't doubt that it would have cycled at one point but I'm trying to figure out why they all died. Unless they spiked and vapidly diminished in between the 3 tests in less than 24 hours. It just doesn't seem very likely.

Why would you plant that many fish in an uncycled system?

Edited by Cecil (see edit history)

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FWIW , I drive 2 hours one way to pick up fish and the dealer puts them in bags with a little salt and fills the bags with pure oxygen.  I open the bag and drop an air stone in the bag during the floatation in the new tank phase while waiting for them to acclimate. 

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In all fairness you will never truly know what caused it. If you decide to get more fish and it works out you may have a hunch as to what caused the problem but you will never know for sure. 

 

 

You say your system had fish in for a long time before these trout and you know your water readings... process of elimination.

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@Cecil

Ok so basically what you are saying is that I should start with less fish? Cool, thanks. I put so many in at once because I didn't want to make multiple trips to a different state, it's costly.

@Ravnis

A little salt? Whys that? When I go back out there I'll try to get plastic bags instead of putting them straight into the cooler. I asked for a bag but he said it was unnecessary. Crazy old man.

@Bcotton

Good point but I want to at least narrow it down as much as possible. Money is tight.

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@Cecil

Ok so basically what you are saying is that I should start with less fish? Cool, thanks. .

No that's not what I'm saying. As sensitive as trout are to ammonia and nitrites you should have done a fishless cycle and then added your fish.

I put so many in at once because I didn't want to make multiple trips to a different state, it's costly.

It's costly to kill all your fish because your tank is not cycled. You might as well dump bleach into the water.

Here's a good read on cycling an aquarium. Same principals with aquaponic and aquaculture tanks.

http://www.drtimsaquatics.com/resources/fishless-cycling

Keep in mind you need more surface space for bacteria in the cooler water your trout require of 55 to 65 F.

Hang in there. You'll get it figured out. We've all killed fish.

Edited by Cecil (see edit history)

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I have transported trout for an hour in a couples of oxygen filled plastic bags with no issues.

 

I don't think 40 fingerlings in 400 gallons of water would be an issue at this stage...It may well be sooner rather than later hopefully the filtration was set up and that doesn't seem to be an issue at this stage...

 

My best guess would be...

 

If you transported them home in oxygen enriched bags you may have an aeration issue even with your air stones.

It really depends on weather or not you transported the fish home in oxygen enriched bags I think...

 

The other thing is you shouldn't feed them for say 24 hours after transport and acclimatising to a new tank as fish are often sick from the transport....You not feeding gives things time to settle down a bit...

 

No quick solution I'm afraid just calculated guesses sorry...

 

Cheers.

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