URGENT HELP: Is weed killing my fish?

[Mr Thompson]

Hi all

Urgent help needed. I went to inspect my pond today to notice a large amount of lethargic fish. The koi were just resting on the top and hardly moving when poked. Then I looked a little closer and a number of the smaller fish (amount 4-5 months old) were dead! What can be causing this? When I moved in 3 years ago, the pond hand gone 3-4 years with a clean or a filter and pump and the fish were seemingly doing fine. I have since got a pump and such and the fish have seemed happy up until today. Even yesterday there seemed to be no problem, no dead fish etc.

Any suggestions?

 

[Mr Thompson]

Update: Just use a test strip and all seems fine on that part.

 

[Mmathis]

Oh my, that doesn’t sound good! Do you have a water test kit and have you checked your water parameters recently?

And in your title you mentioned “weed,” yet I didn’t see that in your post. What kind of “weed” are you talking about?

How big is your pond and how many fish do you have? Fish grow (and reproduce) and as they grow they produce more waste. This changes the dynamics (balance) of the aquatic environment.

Also, could there have been any chemicals that got into the pond (“weed”) either via environmental factors (lawn or pesticide chemicals)?

 

[Mmathis]

Update: Just use a test strip and all seems fine on that part.

We recommend liquid drop test kits (more reliable), and please tell us the actuall results as “all seems fine” doesn’t tell us anything.

 

[Mr Thompson]

Please see some pictures. The photo of test kit I used, the colours never reached the "change water" stage. I currently got the hose showering the pond in case it's an oxygen issue. So sad at the moment.

 

[addy1]

Welcome to our group!

How many fish and how many gallons is your pond?

 

[Mr Thompson]

Welcome to our group!

How many fish and how many gallons is your pond?

Probably about 4 goldfish and 4 carp. And then about 40 or more juvenile fish. Not too sure about the gallons.

 

[addy1]

Is that a layer of thin ice on your pond?

 

[Mr Thompson]

Is that a layer of thin ice on your pond?

No, just camera reflection. I thought it could be a case that the algae or weeds were sucking oxygen out of the pond. Most of this fish are now huddled in a corner.

 

[Lisak1]

Lack of oxygen sounds plausible, but I wouldn't blame the plants. Too many fish would be more likely. All of that string algae is indicative of bio-overload as well. What are the pond measurements? We can help calculate pond volume. How big are the koi in this pond?

 

[Mr Thompson]

Lack of oxygen sounds plausible, but I wouldn't blame the plants. Too many fish would be more likely. All of that string algae is indicative of bio-overload as well. What are the pond measurements? We can help calculate pond volume. How big are the koi in this pond?

Sorry, don't know if this makes a difference but I made a mistake by saying they are Koi. Just standard carp about 8 inches. The pond is about 2mx1mx1m (at the deepest point). Picture of it empty is below if that helps.

 

[CometKeith]

No, just camera reflection. I thought it could be a case that the algae or weeds were sucking oxygen out of the pond. Most of this fish are now huddled in a corner.

Hi. Sorry about your fish loss. It sounds like the pond can't support the number of fish you have without changes being made. My guess when you have sudden fish loss and no obvious signs of disease it can be blamed on a lack of dissolved O2. I would remove the blanket weed so there is better water movement and try adding an aerator and something else to move the water around and see if that helps. Also there is no reason to have that much algae in a mature pond so you most likely are overfeeding.
Hmmm.....Also just saw your picture that your posted of the pond being cleaned. The algae on the liner play an important role with degrading fish waste into less harmful elements by the nitrogen cycle so you really don't want to overly clean it.

 

[Lisak1]

but I made a mistake by saying they are Koi

Interesting - are they wild caught?

I would still say the pond is overloaded - again, all that string algae is telling you that you have too many nutrients in the water. So either too many fish, too much food, or both. More aeration would help and I would get some string algae out, just to improve water movement in the pond.

Based on your measurements, your pond is well under 500 gallons (the deepest point appears to be very small). That would be a good size for a few goldfish. You're estimating nearly 50 fish - that's a lot for a small pond. Were all the babies born in the pond?

 

[Mr Thompson]

Interesting - are they wild caught?

I would still say the pond is overloaded - again, all that string algae is telling you that you have too many nutrients in the water. So either too many fish, too much food, or both. More aeration would help and I would get some string algae out, just to improve water movement in the pond.

Based on your measurements, your pond is well under 500 gallons (the deepest point appears to be very small). That would be a good size for a few goldfish. You're estimating nearly 50 fish - that's a lot for a small pond. Were all the babies born in the pond?

Yes, all the babies were born in the pond. I tried to put some in a fish tank when they first arrived but some died. Thought I would wait for them to get a bit bigger before selling them on or trying the tank again.

 

[mrsclem]

To me it looks like the algae is almost completely filling the pond. I would pull out most of it by hand, don't use chemicals. Looks like the babies are small but you will need to rehome them soon.