My fancy tail goldfish is 7 years old. The last few days he has been acting odd. He is in a 130l tank by himself and I recently done a water change exactly how I usually do it for the last 7 years.

He looks like he was gagging to be sick and his gills are flapping wide open. (This has never happened before) I had a look in his mouth for a stone or rock and couldn’t see anything. (I did this using a net so I could see right in) He is eating occasionally however not like before. I have also noticed today around the colour part of his eye he has black areas which are new.

Any ideas what is wrong?

I forgot to add he is also sitting at the bottom of the tank. He does swim around but 90% of the time he is sitting on the bottom

Many thanks

Sorry to read about this. From your description, I would have thought he'd ingested some gravel. It's possible it may have gone further back / been swallowed, and he may try to pass it out the other end.

What are your readings for ammonia, nitrite and nitrates, using a liquid-based test kit? Although you haven't changed your tank maintenance regime, it's possible that the water supply maintenance has altered a bit, which can sometimes lead to alterations in water quality.
Does your water company use chloramine and, if so, does your water conditioner address that?

Hi. Thank you for the reply. I check the water this morning and all water readings are good.

He is trying to eat but just ends up spitting it back out?

If it is gravel will he be able to pass it?

Thanks