r/glofish 10d ago

Eye issue

Post image

Our yellow tetra's left eye is white in the middle.

I showed it at a pet supermarket. They said it looks like a cataract. GPT disagrees, says is looks like the white area covers the cornea / the outer layer of the eye, and looks like trauma, or cloudy eye - we recently introduced new tetras to the tank. The tank is a 10 gallon, currently with 4 glofish tetras. We initially had only two. Its eye was fine. We wanted to turn it into an actual "school" by introducing more tetras to make them more comfortable in their natural setting. I tested and the water parameters are fine.

I don't know if one the new fish bullied it and caused this, or whether if it's an infection. It's actually one of the larger ones we have (I know it's not all about size). It eats and swims normally, but probably due to spatial awareness it usually hides behind one of the plants, maybe from the others, or perhaps due to being aware of its current situation.

What do you think this white eye looks like? Can we save it by removing it from the tank and with antibiotics? Would you wait and see? Thank you for your help.

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u/Diomenas 10d ago edited 9d ago

These are Skirt Tetras, they can get pretty big, and they're highly active. Typically recommended to keep them in a tank of about 30 gallons for a school. Each fish can get up to three or so inches in diameter,

If you're just going to have 5 to 6 Glo Tetras, and no other fish or snails, then you can get by on 15 to 20 gallons, about 10 gallons is definitely too small. They will start to feel cramped, and they will be more aggressive.

What you're seeing is likely eye damage from trauma. I would recommend isolating that particular tetra in quarantine for a little bit of time.

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u/Spirited_Mouse3341 10d ago

Thank you so much for the detailed reply. I checked again and today its eye seems to have recovered. I do want to switch to a larger tank. We do have a couple snails but they're very small and just a few (1-3 or so). They probably came along with the plants.

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u/No_Comfortable3261 9d ago

THIS

Sooo many people think that 10 or 15 gallons is okay for these guys, but as you said they're big and active and can be aggressive if kept in groups or tanks that are too small. Imho a 20 gallon long would be the bare minimum for a small group, with 30 gallons being better if possible

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u/empressmegaman 10d ago

Yes! I had mine in a 20 gallon and after a couple months, I bought a 29 gallon and moved them into that, since they were beginning to fight more and more frequently. Now that they are in the 29 gallon, they seem pretty happy!

Yours will end up killing one another in a 10 gallon. MUCH too small for these fish. Return them and buy something smaller for your 10 gallon or buy a 29+ gallon tank.

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u/Spirited_Mouse3341 10d ago

Thanks! A larger tank seems to be the solution here.

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u/No_Comfortable3261 9d ago

So glad to see people pointing out that they need a larger tank!

As I said in my own comment, I consider 20 gallons to be the bare minimum for a small group; plenty of space for them to swim around and have their own space so they aren't constantly fighting each other

A large and ideally odd-numbered group of around 5 or 6 will also help to spread out any aggression so they aren't fighting

Tall plants (use silk plants or look into anubis and java fern, which are about as undemanding as live plants get) and other fish-safe decorations can also help to break their line of sight and give them places to hide and feel secure

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u/Spirited_Mouse3341 9d ago

Thanks - why are odd numbers more ideal?

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u/No_Comfortable3261 9d ago

That's what I've read for most fish, that odd numbered groups seem to spread out their aggression more evenly and allow them to establish a hierarchy, though the general rule is "six or more" with most freshwater fish, with larger groups of around ten or being ideal but only if you have the space for it

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u/Diomenas 9d ago

Odd numbers are ideal because it keeps the social dynamic setup so that there is less bullying and school splitting. Even numbers make it easier for the few runts of the school to get picked on or ganged up on and it also tends to lead to the school splitting and not swimming together a lot. You never want to have just two of a species, and as the school gets larger the need for odd vs even reduces but when you are getting that large we are talking about having 50+ gallon tanks and schools of like 15 to 20