ADVICE NEEDED. Goldfish dying off.

[LondonPond]

Hi guys/gals

Keen to get some advice to try and understand why my goldfish are dying off.

Pool is an above-ground dish shape 120cm diameter and 35cm at the middle making c.200 litres.
We have several submerged rocks for cover, a submerged barley bail for algae management, 5 pond plants (inc pond lily, fibre optic, Dutch rush, marsh marigold, hycynith) and a basic (non-filtering) pump/fountain in the middle with the water stream breaching the surface by 2cm.
Algae grows on the pond sides but clarity is generally good.

We added 10 goldfish (between 4cm and 7cm) on 4th June and feed maybe 10-20 fish food nuggets each day which they have been eating.
I’ve noticed them at the surface, presumably eating mosquito larvae and such.
They are easily spooked and move quickly when they see us but otherwise quite stationary hanging out under cover. This is different to when they were first put in and vigorously swam round in circles at the surface.

All was well for a couple weeks but since then I’ve found single dead fish a few days apart from each other. We’ve lost 4 total so far.
Apart from one, which had scales missing, they are otherwise perfect... but dead.

What are your thoughts on why?
What can I do differently to sustain them?

 

[Mmathis]

Hello and welcome!

I can only speculate, but my guess is that you added too many fish, too quickly to a volume of water that is too small for that many fish. Plus, you don’t mention any kind of filtration or aeration (other than plants). Not only that, but any rocks or stones that were added will take up volume, displacing water, essentially making your 200 liter (or approx. 52 gallon) even smaller. But, it is fixable. Do some research on the nitrogen cycle — if you’re like me, look for something geared toward “nitrogen cycle for dummies.” There are numerous posts on GPF that explain it very well, or use Google search. Goldfish excrete ammonia which is harmful. Think of it like a human being in a closed room with a dozen smokers — it’s hard to breath the air and it’s not good for your health.

I suspect that your ammonia and possibly nitrite levels are high, and there is no baseline for the pH. This is toxic for fish. Do a few small water changes (add a de-chlorinator if your local water source is treated). There are also products that you can buy to reduce ammonia, but these are only temporary solutions. Also, you might consider rehoming some of the fish — or do like most of us have done, and build a bigger pond!

Can you get a water test kit — we recommend something like API Master test kit, and as an add-on, the KH and GH kits? This is a liquid, drop test kit. This type of test, though not as convenient, is more accurate and reliable than test strips.

Test your pond for ammonia, nitrates, pH, nitrates, and KH. Get back to us with those results. In the meantime, add some movement to the water — can you get a small pump and/or an air pump? (Air pumps need to be covered, so don’t leave it exposed to the weather.)

 

[Lisak1]

@Mmathis shared the information about the nitrogen cycle that most of us would have, so I will leave that topic alone. But in addition is it always possible that they fish you brought home weren't in good shape to begin with. Lots of places sell fish, but they don't always know how to sell HEALTHY fish.

Going forward, I hope your remaining fish survive but if not, your small container pond would be perfect for two or three goldfish.

 

[LondonPond]

A lot of that makes sense.

I do have a small pump creating a small fountain to add movement and air bubbles
(https://www.pond-planet.co.uk//pond...ontec-pondovario-750-fountain-pump-p571/s1019)
Is this not sufficient to aerate, do you think?

We’ll not be building a bigger pond and ideally I want a low-to-no maintenance habitat.

Is there a rule of thumb of X litres per goldfish?

 

[Mmathis]

@Lisak1 Thanks! I knew I would leave something out!

@LondonPond Also wishing you well. Your plants look nice and healthy. Can you post some pictures of the entire pond? We love to see what other’s ponds look like.

 

[j.w]

@LondonPond

 

[LondonPond]

@Lisak1 Thanks! I knew I would leave something out!

@LondonPond Can you post some pictures of the entire pond?

Thanks. It’s my first pond.
It’s a fibreglass shell with real verde gris (copper paint + oxidiser to give it that lovely patina). Mrs Wife is responsible for acing our florals!

 

[mrsclem]

Was the inside of the pond painted? Copper is toxic to fish.

 

[LondonPond]

Was the inside of the pond painted? Copper is toxic to fish.

No, only the outside (although I didn’t know that). We had a single goldfish survive in there for a year before we added 10 mates.

 

[AlyssaFish]

Is there a rule of thumb of X litres per goldfish?

This is a highly contentious subject, but in my own, personal experience, 30 gallons (113ish liters) per goldfish seems to be enough for a healthy ecosystem. I had 10 4-5" fish in a 300 gallon pond without any troubles.

Keep in mind that you can't just dump 10 goldfish in a 1,135 liter pond and expect them to do well. Because of how slowly the nitrogen cycle is established, you have to be very careful about the number of fish added to a pond at once. At the very start of the cycle, add a single goldfish and watch the water parameters every day. If ammonia, nitrites, and nitrates all stay low, it's safe to add another fish. Once you have 3 fish in the pond with no water parameter issues, you can consider adding 2 more fish at a time--but again, make sure to watch water parameters very carefully.

Since you already have all your fish and can't really do a slow introduction, you may have to do partial water changes every day to keep your water parameters at healthy levels. Are you familiar with the nitrogen cycle and water parameters? I know a couple of people have already mentioned it.

It's a very lovely setup, by the way. I am sorry your fish aren't doing well at the moment.

 

[LondonPond]

Thank you. Very interesting. I’ll buy some testing kit immediately and will do the daily partial water change.

I’ve noticed all the fish come to the surface ‘gasping’ and blowing a few bubbles. Is this normal or indicative of the ammonia nitrate cycle imbalance?

 

[Mmathis]

It could. Do you have a way to check the temperature of the water?

 

[mrsclem]

Can you get an aerator to add some oxygen to the water? your fountian may not be enough. Check the temp of the water and shade the pond if possible. It's possible you got some unhealthy fish and that is why you are having problems.

 

[IPA]

Not sure if it was mentioned but stop feeding the fish. You could purchase something like stress coat, it is also a dechlorinator

 

[LondonPond]

Not sure if it was mentioned but stop feeding the fish.

I’m assuming this is only a short term suggestion until nitrate levels balance? Can’t stop feeding them per se, right?