Lethargic Telescope Goldfish

Question
Hi, I have had a telescope goldfish for over a year and I got a larger tank and light for them in December. In the last few weeks he spends alot of time sitting under the filter, fin's drooped down. He has two small fins under his tail and one is stuck on the outside of the tail but apart from that appears normal and is eating. I also have two black moors which active and healthy.

Answer
Hi Sofia,
When fish behave listless in this way, it always calls for investigative work done on the tank's environment, all the aquarium occupants, the appearance and behavior of all the individuals, and the care given to the fish.

While you mention your two black moors are doing well. It never hurts to check the water quality of the tank by testing for ammonia, nitrite, and nitrate. If ever in doubt of these levels being where they should be - (ammonia- 0 nitrite - 0 nitrate - under 20) a 30-50% water change is definitely in order.  

Is it possible the telescope goldfish is getting intimidated and bullied by the other goldfish? Does the telescope venture out and swim around comfortably when its meal time? Does he have a tilt or balance problem when he swims? I know this can be hard to pinpoint because these fancy goldies naturally have a wobbly-way of swimming but over-exaggerated awkwardness when swimming such as tilting over or nose diving can signal a swim bladder problem. A very common condition in fancy goldfish breeds.

Constipation is also a possible cause for making fish sluggish. Fasting the fish for at least 2 days and offering mashed green peas as their only meal for at least a day or two usually helps conditions like this.

Unfortunately, internal disorders which are nearly impossible to properly diagnose without help of a fish veterinarian could also be responsible. However, you would likely be seeing other physical signs of distress if this were the case such as heavy/fast breathing, swellings on the body, skin discoloration, and very low to non-existent appetite.

The fact that the telescope it eating is a good sign he's probably not in serious condition. But I would check the water and just in case- (since goldfish are big polluters), do a 30-50% water change on the aquarium. Always making sure the replacement water is treated with a water conditioner and the temperature is equal to or just a bit warmer than your tank's water.

Keep a close eye on him and try offering some green peas as well to his diet.

I do hope this helps!
Karen~