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Dr. B.
Dr. B., Board Certified Veterinarian
Category: Veterinary
Satisfied Customers: 20547
Experience:  General practice veterinary surgeon with extensive experience in a wide range of species.
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I have a goldfish with a tumor that has grown to about 1.5

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GoldfishI have a goldfish with a tumor that has grown to about 1.5 inches in the last few years. He lives in a 40 gallon with 2 dojo loaches (40 gallon tank has 30 gallon sump) He has existed peacefully with my dojo loaches for a long time but recently I've noticed the dojo loach nibbling on the Goldfish's tumor. Last night I saw that the goldfish is missing a huge chunk of the tumor. It looks like it is being eaten by the Golden Dojo loach. As of last night, my goldfish doesn't want to eat and he floats towards the surface. I can tell he is in distress but I am not sure what to do. He is a big fish about 5-6 inches in length and weighs alot. He is about 5 years old. I am thinking of separating the Golden Dojos into their own 26 gallon tank. What do you guys think? Have you guys seen this kind of behavior before?

Hello & welcome to Just Answer/Pearl. I am Dr. B, a licensed veterinarian and I would like to help you with your wee ones today.

I would strongly advise that the goldfish be isolated from other fish to protect him from further damage by his 'friends'. The behavior you have is not uncommon to fish and it is quite likely that with the now open wound this fish may be attacked again. Loaches are carnivorous and carnivorous fish can 'pick on' weak/sick fish. (Loaches are not alone in this. If the roles were reversed, the goldfish would have done the same to a loach. And if you look at your fish food the majority are primarily composed of fish meal). As well, if the mass had been outgrowing its blood supply there may have been some mild tissue necrosis present and this would have further attracted the loaches to it. Therefore, in regards XXXXX XXXXX question, the behavior is very common and you will likely see it again if they are kept together.

Now in regards XXXXX XXXXX goldfish, I agree with your ruling out bacterial and fungal triggers for the mass. In fact, if we were considering a trigger (other then traditional cancer form dysfunction cancer cells) we most commonly see goldfish tumors triggered by viral causes (usually herpes). But no matter what the trigger for the mass was, I would say that the goldfish's current behavior does raise concerns that he may be in shock or secondary bacterial sepsis may be present. Therefore, since you are due to isolate him, you might consider supplementing him with some aquarium salt (for shock, start at a 0.1% dose) and covering him with a broad spectrum antibiotic that will cover against aeromonas (the most common bacteria that infiltrate wounds in fish). In regards XXXXX XXXXX choice, kanamycin/doxycycline would be a good option. If that is not available, then you can treat with erythromycin (plain Maracyn) or tetracycline, but treat simultaneously with minocycline (your Maracyn-Two) for the Aeromonas.

Overall, the behavior is not uncommon but is rather one of opportunism that is common in carnivorous fish. But in this case, you need to isolate this fish to protect him from further damage and support him to get him through this traumatic event.

I hope this information is helpful.
Please do let me know if you have any further questions.
If you have no further questions, feedback is greatly appreciated.

All the best,

Dr. B.


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Customer: replied 4 years ago.

Dr. B. Thank you so much for your answer. It was very thorough. I have two more questions. I only have a 10 gallon hospital tank. I believe the minimum for a fish of his size would be 20 gallons. Can I keep him in the 10 gallon while he receives treatment? I currently have Kananycin (powder formula) and MediGold (food pellets with sulfadimethoxine and ormetorprim sulfa). Can I give him both? After treatment I will move him to the 40 gallon and put the dojo loach in a 20 gallon long.

You are very welcome.

It would be ideal if the hospital tank was bigger but as long as you keep a close eye on the water parameters it should be fine. And sounds like the relocation of the loaches and goldfish (after treatment) sounds in order.

In regards XXXXX XXXXX choices, it would be fine to use both together to widen your treatment spectrum as both products have different mechanisms of action. And since you noted that his appetite is poor, having the kanamycin on board will ensure that he does have some if good antibiotic coverage even if he won't eat the Medi Gold.

Best to you both,
Dr. B.
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