My comet Goldfish

Question
QUESTION: Hello, Dave...

I have a male comet goldfish 3 1/2 years old, healthy, roughly 14/15 inches from tip of nose to tip of his very long tail and living in a 90 gal aquarium - alone.  His mate died 6 months ago and since then I've chosen not to get him another companion.  Prior to her death (undetermined, but leaning toward a generic problem), the tank was beginning to look a little small for the two of them. She was the bigger of the two.  Now, he's grown to his present size and I want the best environment for him.

I'm considering doing one of the following, despite the fact that he looks like he's doing fine as he is, I'm concerned about him needing other fish around:

#1 - Adopting him to fellow fish lover I met, who has an outdoor comet/coy pond.  My only fears here are temperature change issues and larger community immunity factors.  However, I've gotten into the pratice of giving him Vit-C soaked Krill as an immunity booster once a week.
  
#2 - Keeping him with me, which would be my selfish desire, and just getting him another companion....maybe a shubunkin.  Need to know who he'd be compatible with and given his size and size of my tank - would 90 gal still be okay?  I'm sure I'd wind up getting a smaller fish, but not small enough for him to bully around or possibly eat.  

Note: Tank temperature is maintained at 74-76.  I do the best I can with this, as live in Florida and I have to keep the air-conditioner running all the time.  My consistent challenge is keeping the nitrates down. All the other chemical levels are fine...I have two testers, chemical liquid w/tubes and test strips.  I do bi-weekly partial changes - usually 10 gal. and one partial gravel vacuum a month.  I have a Fluval 405 Filter and plenty of aeration.  I change the carbon in the filter every month.

I'd greatly appreciate any advice.
Thank you....Annie


ANSWER: Hi Annie:  Goldfish are happy to live by themselves or with other fish... They are not shoaling fish like many of the tetra are.  He is fine in the 90 gallon tank and could have 1-2 more fish that are about his size with him.  However, I would suggest maybe something new... try a blue phantom plecotomus which are very beautiful and beneficial to the tank.  You could also incorporate eels in the tank... though I would lean more towards dojo loach or weather loach even a peacock eel or three.  You could also add in a small shoal of butter fly koi... 1-3 of them... etc.   There is no need to put him in a pond... you could if you wished too but he is perfectly fine in the tank... dave

---------- FOLLOW-UP ----------

QUESTION: Dave...thank you

I just need a little more clarification based on my original submission.  So - these newer type fish, esp. as you said, a plecotomus - how would it benefit my tank?  If it's a bottom feeder, "Louie" already does that himself.  Eels don't appeal to me, as I'm squimish already w/snakes.  I'll have to look up what a loach is and all the others you suggested.  Also - what about a shubunkin?  Lastly, based on how I told you I'm maintaining my tank....w/chemicals, etc., do you think I'm missing anything in it's care?

Thank you again....Annie

Answer
The plecostomus would benefit the tank because it not only cleans the bottom but the glass too.  It will also be another fish in the tank that will not present an aggression issue either from Louie or towards Louie.  You can buy them when they are small and they will grow without danger of Louie eating them.  The only thing I would do is to add some aquarium salt per its instruction label.  Shubunkins are fine too.... dave