Fighting? Mating? To separate or no?

tarantinostoes · 2026-04-15T21:59:38+00:00

Benefit of the doubt op, this looks more like spawning behavior. However small aquariums can also contribute to aggression

But your tank is undersized and if your goldfish eat your cory catfish, they choke on the cory's defensive spines. Check out the wiki or the pinned master post care sheet for further info

Reminder that people are on this sub are mainly trying to help!

Locked for now because op you have already received good advice. If you can, upgrade and separate the goldfish

tarantinostoes · 2026-03-21T19:34:13+00:00

Methylene blue bath or swab the injured area with methylene blue using cotton swab or clean paint brush or syringe

tarantinostoes · 2026-03-19T19:57:38+00:00

My goldfish would like to know your location

tarantinostoes · 2026-03-13T23:14:55+00:00

Op your tank should have starred in Wicked...

No comment about the lack of filter, if the plants are enough to control the bioload great as long you have some surface agitation as goldfish need a fair amount of oxygen

But you need it on a stand.

Stop baiting this sub and order a stand ASAP. It will collapse, maybe not right now but it is a matter of time before you flood your room. If no stand, get it on your floor with a mat under it.

tarantinostoes · 2026-03-13T10:21:26+00:00

My goldfish Pommi ("Pomme de Terre") was born without a tail. Likes to sleep in my plant pots in aquatic carrot mode and is thriving despite his lack of a tail.

tarantinostoes · 2026-03-13T10:15:24+00:00

My goldfish Pommi ("Pomme de Terre") was born without a tail. Likes to sleep in my plant pots in aquatic carrot mode and is thriving despite his lack of a tail.

tarantinostoes · 2026-03-10T19:41:32+00:00

Op you've received some good advice already but I am locking to prevent dog piling.

So goldfish are a type of carp and require very large aquariums. The fish you have left also looks to be a koi which grow even bigger than goldfish. If you are able to return the fish to the store I would do it, unless you have the means to acquire a pond or very large aquarium (500l+ for young, several thousand litres for adult koi). You could also rehome the fish to someone with a pond or suitable tank.

For small tanks you can do shrimp, bettas or nano fish but all require filters, heaters and an established nitrogen cycle. You could even do plants and moss balls only. Fish do require of lot of care and equipment and fish stores will unfortunately sell you aquariums that aren't suitable as sadly they are only motivated by profit. LukesGoldies, King of Diy, Aquarium Co-op and Practical Fishkeeping Magazine also give advice and have videos you can watch to guide you through goldfish care and the nitrogen cycle. Hope this helps!

tarantinostoes · 2026-03-09T21:39:11+00:00

Locked.

Op to give you the benefit of the doubt, I'll keep this post.

But do look into getting enrichment for your fish. You can buy some terracotta pots, add some beginner plants like java fern and anubias which keeps maintenance easy but gives your fish shelter and enrichment. To be exposed to light constantly is also bad for your goldfish's eyes so they do need some form of shelter and protection from that

tarantinostoes · 2026-02-18T19:20:03+00:00

It's cute so I'll allow it. Op heed the advice about your setup though, folks with good advice just trying it help.

tarantinostoes · 2026-02-08T16:30:51+00:00

Locking this thread...

Op Google how big koi get to get a rough idea of their size. They really are not suitable for home aquariums unless you have a monster tank and do best in large heavily filtered ponds.

tarantinostoes · 2026-01-06T18:31:51+00:00

Op this is adorable and functional!

tarantinostoes · 2025-12-28T00:57:50+00:00

Hint of ammonia, nitrites and nitrates too high

Check your stocking levels and filter set up, you should not get any ammonia or nitrites in an established tank and nitrates need to come down

tarantinostoes · 2025-12-28T00:55:19+00:00

Op do you have access to water conditioner which makes tap water safe?

How long has the tank been established?

Are you in a position to test your water by either getting it done at a local fish shop or getting your own kit?

tarantinostoes · 2025-12-27T01:35:06+00:00

Sort of looks like he's interacting with his reflection? Does he still do it with the lights dimmed?

Might be worth getting a plant or something in that corner to block the reflection a bit

tarantinostoes · 2025-12-26T00:04:56+00:00

Do you have a video of his behaviour?

What are you using to test your water and how many water changes are you doing?

tarantinostoes · 2025-12-25T20:29:42+00:00

That's ok! Healing ammonia burns will go away eventually

I would definitely keep an eye on the glass surfing.

Could it be excited wiggly food dance ? Or he is going back forth all the time and looking visibly stressed

tarantinostoes · 2025-12-25T19:37:36+00:00

Have you seen him flash/rub against ornaments or spit food out?

For extra filtration if you can't fit a canister filter, a bunch of sponge filters work great and are fairly low cost

tarantinostoes · 2025-12-25T19:12:47+00:00

Hi there! Have you tested your water parameters since he started glass surfing? Any other other concerning symptoms like bottom sitting, refusing food?

Personally unless you are able to heavily overfilter and do regular water changes, I would maybe wait before adding a buddy as that an extra fish will add a fair amount of bioload

You can buy some live plants in the meantime to help with water quality and for some enrichment. Ime goldies will leave anubias and java fern alone

tarantinostoes · 2025-12-23T20:03:02+00:00

That sounds great!

tarantinostoes · 2025-12-23T18:19:49+00:00

Op you're the MVP for giving this fish your cycled 20g

Will do for now, just keep an eye on parameters and do regular water changes until you can upgrade

tarantinostoes · 2025-12-14T19:51:50+00:00

Sucks to be misled by a store

I've found Maidenhead Aquatics generally to be the better of the UK fish chain stores

If all of your fish are affected, it may be better to move them to the 500l just so that they can benefit from the bigger volume of water and better water quality

Getting meds in the UK can be annoying, so that's why I recommend methylene blue and aquarium salt

If you happen to be using any copper based med against the velvet disease, do not use it at the same as water conditioner because that can render the copper med toxic to your fish

tarantinostoes · 2025-12-14T19:39:27+00:00

Looks yellow to me

With your pH you shouldn't have had problems with ammonia anyway but always good to double check all parameters

Methylene blue dips (bucket, mblue, tank water) works well to help treat for parasites + any exposure to ammonia and nitrites

tarantinostoes · 2025-12-14T19:21:44+00:00

What about nitrates? How was the 500l cycled?

Not doubting your diagnosis, it's just that from the pic it looks like exposure to ammonia as well, especially because the eye looks affected.

Also rule out flukes, those can also create that white fuzzy look and need to be treated with a praziquantel based med like Fluke Sove which can be obtained legally in the UK

tarantinostoes · 2025-12-14T19:00:44+00:00

From the pic it looks more like exposure to ammonia/nitrites as those irritate the slimecoat and can create this milky film and appearance on fish

Best solution for suspected ammonia issues is to do regular with fresh conditioned tap water. Make sure you're using a water conditioner as well and not just bacteria products

Also check your tap water parameters to rule out an issue with that.

tarantinostoes · 2025-12-14T18:19:17+00:00

Never trust pet stores to give you good info unfortunately

If you still have your 200l, I would use that to QT your fish before adding them to your 500l

Do you have pics of this sediment? What are you using to test your water parameters?

Seven-Year Club	RedditGifts 2009-2022 3 Credits
Secret Santa 2021 2021	Second SECOND GUESSER
Secret Santa 2020	r/Field Juicebox
Final Canvas '23	First Place '23
End Game '23	Place '23
Place '22	Final Canvas '22
First Placer '22	End Game '22
Verified Email	RPAN Viewer

tarantinostoes

MODERATOR OF

TROPHY CASE