Fish health?

[Gavin Adcock]

I’m entering the 4th season of my 3000l pond, described here :

Newbie question about silt cleaning options

I'm new to the site and new to pond ownership - please be gentle! I built a pond last spring (2016) in an unused garden feature (large raised flowerbed behind a granite bench). It's about 7m long and a little over 1m wide (roughly rectangular). There are 3 shelves of differing depths with an...

www.gardenpondforum.com

In the first season, I added 5 or 6 goldfish which within weeks had reproduced to become around 100. They quickly established a balance with around 30, the 4 or 5 originals about 5cm in length, the new generation a little smaller. We lost 1 or 2 per year (that I could count) over years 2 and 3. I haven’t been able to make a clear count this year but there are probably around 20 now, let’s say 5cm on average. One of the originals is still there and might be 10cm long. I don’t feed them.

Coming out of this winter I have found bodies on 3 separate occasions. Is this normal attrition with the fish stocks balancing themselves out and/or old age, or should I be concerned? Is there anything to look for when a fish dies that helps diagnose any problem?

Water is pretty clear, slightly cloudy now but I expect that to clear up as the plants grow back. I don’t measure water quality.

Thanks in advance, Gavin.

 

[Lisak1]

I remember your pond - very pretty!

You shouldn't routinely have fish dying - that's not normal. But without testing the water it would be hard to say if it's a water quality issue. Maybe it's too many fish? Maybe they were the weaker of the lot and couldn't handle winter? If they don't appear to have been attacked by a predator, I guess you just have to keep watching and observing the remaining fish.

 

[Gavin Adcock]

I doubt water quality is an issue. Rain water is diverted from the roof so it is regularly refreshed. I’m running a filter and pump for aeration (no UV this year), there’s no sign that the fish lack oxygen. I’m thinking/hoping it’s natural attrition, like you suggest, and that my pond is perhaps overstocked.

 

[Lisak1]

I will caution you that there are those who will frown on allowing water from your roof to go into your pond - they fear the debris that settles on the roof or even the materials the roof are made from or treated with might harm the fish. Personally I don't have a problem with it, but it's something to consider if your fish die off continues.

 

[Gavin Adcock]

I can agree in principle except that there is next to no debris on my tile roof and nothing has changed recently in that setup.

 

[mrsclem]

Water testing will tell you if you are overstocked. Elevated ammonia levels.

 

[Gavin Adcock]

I’ll add a water tester to my birthday list.

Is overstocking a likely cause of fish dying? Do they tend to die off as they grow assuming unchanged conditions such as water volume and food sources?

 

[mrsclem]

Yes, that is a big cause of fish loss. People always say- I've had my pond for years, nothings changed. Fish grow, they produce more waste, water quality goes down. Do you know how many gallons your pond is?

 

[Gavin Adcock]

3000 litres, which the internet tells me is 800 US gallons.

 

[mrsclem]

With 20 fish under 3" I don't think you are overstocked. Get that test kit and post the results.

 

[Spartamets]

Fish don't die unless something is killing them (or they're really old). So something is amiss. It could be fish load, but that is more of a blanket observation encompassing culprits like lack of adequate filtration, pathogens in the water, insufficient oxygen, etc. A fish load is only excessive in relation to the pond's ability to process fish waste, and many variables go into that. Plants tend to be real good problem solvers. The introduction of pathogens from birds or elsewhere is a separate issue; more accurately the inability of your fish's natural defenses to handle those pathogens is a separate problem--though it can be related to "fish load," too. It can also be a function of those pathogens "waking up" after winter before the fish defenses do.

 

[Gavin Adcock]

Thanks for all the replies - food for thought.

I'll buy a test kit ASAP. Funnily, a quick internet search shows lots of inexpensive kits but almost none have ammonia as a test criteria (but do have nitrites and nitrates). Is knowing ammonia levels essential or does nitrites/nitrates tell me enough?

I was thinking about what might have changed this year:
1. No UV light. The bulb broke sometime last season so I decided to try without one for a season. I'm still running a pump/filter.
2. I added rocks. This was partly aesthetic, partly to increase surface area for bacteria, partly for the pond life to hide. Most rocks came from a dry river bed, although some came from the edge of a farmers field. These were pressure washed before going into the pond.
3. We had unusual weather with early warmth and then cold temperatures (snow in May!). Maybe this strained to fish's immune system?
4. Another year of natural progress - fish are continuing to grow as are the plants. I am at the tricky stage in the season where plants (mainly lilies) are starting to grow but have not covered the water surface yet. The water is slightly cloudy and I'm getting deposits of fine brown silt over the rocks. I'm trying to be patient here and hope everything clears up naturally (previous years I connected a second pump/UV).

Any wisdom out there?

 

[Lisak1]

1. UV - wouldn't affect fish health one way or the other.
2. Rocks - could have been contaminated from the farm field, but then all the fish would be affected, so probably not.
3. Weather - these are goldfish. They're pretty resilient.
4. Fish overload is the most likely answer in my opinion, which water testing would give you the best clues for diagnosing that.

API test kits are the most often recommended here - the drop test, not the strips.

 

[Gavin Adcock]

I neglected to act on this until I found another floater this week. Got a test kit quickly which showed me most values were poor - high nitrites, pH, carbonate hardness. As solutions suggested a 30% water change, that’s what I did today, filling with tap water. Still have high carbonate hardness (so does my tap water) but pH (was 9.7, now 8.0) and nitrites (1.12, now 0.34) are in the normal range. I guess that’s what was killing my fish... BTW, it’s a simple Tetra 1-in-6 test strip kit so I’m not convinced by the degree of accuracy this data suggests.

So, the solution is simple - Monitor the water levels, change water if needed. This should normally happen naturally as rain water is diverted to the pond, but this year has been exceptionally dry.

Thanks to all for inputs. Any (beginner) advice out there on what explains high pH and nitrites? Fish poo?

 

[mrsclem]

The test strips are not accurate. Pick up a liquid test kit. Ph of 8 is fine, does the strip test for ammonia?