Two adult goldfish sitting on tank bottom

[Champanier]

Tank
What is the water volume of the tank? 55 gallons
How long has the tank been running? 1 1/2 years
Does it have a filter? 2 Aquaclear 70s, Seachem Tidal 110
Does it have a heater? Cobalt
What is the water temperature? 74°
What is the entire stocking of this tank? (Please list all fish and inverts.)
2 adult goldfish (common 10”, shubunkin 8”)
About 20 goldfish fry (1” to 3”), 4 months old
1 Siamese algae eater
1 dwarf flash pleco 1 1/2”

Maintenance
How often do you change the water? Every 3-5 days
How much of the water do you change? 50%
What do you use to treat your water? Nothing (well water)
Do you vacuum the substrate or just the water? Substrate

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes
What do you use to test the water? API master kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: .25 ppm
Nitrite: 0 ppm
Nitrate: 0 ppm (was 5 ppm before water change 4 days ago)
pH: 6.8

Feeding
How often do you feed your fish? Once a day (I skipped a day when they first were at the tank bottom in case that would help)
How much do you feed your fish? About 30 pellets for the whole tank
What brand of food do you feed your fish? Omega One medium goldfish pellets
Do you feed frozen? No
Do you feed freeze-dried foods? No

Illness & Symptoms
How long have you had this fish? 2 years
How long ago did you first notice these symptoms? 3 days ago
In a few words, can you explain the symptoms? Both large goldfish are staying mostly in one spot on the bottom of the tank. They occasionally swim around as normal, and they come up to eat.
The young goldfish and the algae eater seem are acting normally, but maybe slower than usual.

Have you started any treatment for the illness? No
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? Appearance hasn’t changed, only behavior as described above. They usually spend their time nibbling on plants and rummaging through the sand.
Explain your emergency situation in detail.
We are struggling to keep up with growing goldfish fry that have overstocked the 55 gallon tank and do frequent water changes. I just found a fish store that will install a 125 gallon tank, but it won’t be here for a few weeks. We rinse out the pre-filters every 3-5 days ( they get filled with sludge) and gently rinse the filter media in a bucket of tank water about once a month. We alternate among the three filters, so they’re cleaned weeks apart. Here are all the things we did recently:
1. Last week, the Seachem Tidal indicator popped up and I took the media basket out to rinse it. When I wasn’t looking, my husband poured the sludgy water from the filter reservoir BACK INTO the tank. We had already drained about 50% of the water. I drained more after he did this, but there was no way to get all the bad water out. We filled the tank with fresh well water (Usually I fill bottles ahead of time and let them rest for a day or more, but my husband just had heart surgery and we ran out of prefilled bottles, so just took water straight from the tap.) I changed the water again about 3 days ago and added Prime this time.

2. I threw away the charcoal pouch and added a new piece of stiff fabric media that’s supposed to help with ammonia (not sure about the brand - it was from Petco.) I also added an extra piece of Aquaclear sponge, leaving the existing sponge in place.)

3. I added a Hygger sponge filter. I soaked it overnight and rinsed it before installing it.)

I don’t understand why only the older goldfish seem to be affected. I’ve been looking for a place to take the smaller goldfish, but wanted to let them get a little bigger because I worried that pet stores would put them in with ‘feeder’ fish.

I’m going to do another water change now.

Include pictures

 

[F1sh]

I'm not sure, but it could be a lack of oxygen maybe? The tank seems overstocked at the moment with all the fry. I know sometimes bigger fish are sometimes more easily affected by a lack of oxygen and are more sensitive about it than younger fish.

 

[FishDin]

Why do you usually let the water sit? Is there a problem with the water? Why are you adding Prime to well water? Is it because of the ammonia? There is no proof (according to Seachem) that Prime helps with ammonia, so don't rely on that even if that is what the label says.

That gunk in the filter is not "bad water". It's aquarium gold and should not cause any issues. Many people pour it into their new tanks to jump start the cycling process. The reason to clean the filter is because it starts to clog, it's not because the gunk is bad.

If there was a lack of O2 I would think the fish would be gasping at the surface.

Your water tests look good. The small amount of ammonia can be handled with water changes. Sounds like you need to keep your tank going safely for just a couple more weeks. I would continue to stay on top of water changes, even daily 10% instead of one big one weekly. If the 2 adults had signs of disease I would suggest you put them in a quarantine tank.

It helps to dim your light or just turn them off to decrease stress.

BTW, nice fish.

 

[Champanier]

Why do you usually let the water sit? Is there a problem with the water? Why are you adding Prime to well water? Is it because of the ammonia? There is no proof (according to Seachem) that Prime helps with ammonia, so don't rely on that even if that is what the label says.

That gunk in the filter is not "bad water". It's aquarium gold and should not cause any issues. Many people pour it into their new tanks to jump start the cycling process. The reason to clean the filter is because it starts to clog, it's not because the gunk is bad.

If there was a lack of O2 I would think the fish would be gasping at the surface.
Your water tests look good. The small amount of ammonia can be handled with water changes. Sounds like you need to keep your tank going safely for just a couple more weeks. I would continue to stay on top of water changes, even daily 10% instead of one big one weekly. If the 2 adults had signs of disease I would suggest you put them in a quarantine tank.It helps to dim your light or just turn them off to decrease stress.

BTW, nice fish.

Thanks so much!
I’m relieved that the filter gunk wasn’t bad!
I let the water sit because it comes out of the tap really cold and because I think I read to do that. (I’ve only been keeping fish for two years, so I still have a lot to learn.) I don’t usually use Prime, but hoped it might help.
Thanks for the water change recommendations. We’re doing very frequent changes (2-3 days) now because the tank is so overstocked with the baby goldfish. Smaller daily changes would be easier.
I took out the Hygger sponge filter. There was at least one Amazon reviewer who said their fish died after adding this filter. My fish perked up a day after I removed the filter. Could be coincidence, but I don’t want to take the chance. Anyway, everyone is active and thriving today!!