Obese/sick Black Neon Tetra?

[Gidge]

Hi all. 
 
I have a 165L/44G tropical tank. Heavily planted with drift wood. I appear to have a very over weight, or, sick Black Neon Tetra. 
 

 
STOCKING:

• 8x Hengle Rasbora
• 9x Black Neon Tetra
• 7x Tiger Barbs
• 5x Sterbai Corydora (Waiting for LFS stock)

 
TANK:

• Cycled - has been running for several years
• No new additions to the tank, fish or plants
• Bare minimum aggression from the Tigers, they generally bully each other.  

 
WATER PARAMETERS:

• pH = 7.0 (A little high I know, but as I said, set up for several years, Perth generally has a high pH)
• Ammonia = 0ppm
• Nitrite = 0ppm
• Nitrate = 5.0ppm Just did a scheduled 50% water change.

 
FISH OBSERVATIONS:

• Does not appear to eat excessive amounts - but eats normally when feeding time.
• Does not get picked on by others
• Swims with the group
• Is not slow or sluggish
• Swims normally - not struggling or losing balance
• Scales are not stretched or protruding outwards
• He is not excessively skinny in other areas such as head or towards the end of his body
• No other fish are appearing like this

 
He has been like this for a few days now, closing in on a week. At first I thought he had eaten a whole lot and was simply fat. 
So i started watching him during feeding time, as said above, he doesn't gobble tons of food, nor is he barely eating. His behavior appears to be completely normal.
 
Any suggestions would be great. Time to put him on a diet?
 

 

[Blondielovesfish]

Is it maybe a she? And "she" is getting ready to spawn?
Sorry I don't know much about theses fish so could be wrong but that's what I think!

 

[PrairieSunflower]

I have one female regular neon tetra that is very much like this. In her case, she DOES eat more than others on top of her size going up and down with eggs. I've reduced her size quite a bit by reducing feeding to the tank.

I'm not sure that it is the same for yours though.

I'd probably start with fasting them for a day or two in case it is simply a bit backed up or constipated.

 

[Gidge]

Is it maybe a she? And "she" is getting ready to spawn?
Sorry I don't know much about theses fish so could be wrong but that's what I think!

That would be interesting! Wonder if anyone can confirm this? 
 
 
 

I have one female regular neon tetra that is very much like this. In her case, she DOES eat more than others on top of her size going up and down with eggs. I've reduced her size quite a bit by reducing feeding to the tank.

I'm not sure that it is the same for yours though.

I'd probably start with fasting them for a day or two in case it is simply a bit backed up or constipated.

 
Sorry I should have mentioned that I did fast them for 2 days. He/she has stayed the same. 

 

[PrairieSunflower]

I think it is quite possibly a female too... though slightly too fat.

 

[Lunar Jetman]

I'd probably start with fasting them for a day or two in case it is simply a bit backed up or constipated.

That must be one big blockage!

With regards to the photo, it's not clear how much bigger it is than the others as the other neons seem to be a bit behind it, making it look even bigger.

I have some Buenos Aires Tetras that were all bought at the same time and were the same size but now vary greatly in size to the point where there is about 2cm between the largest and smallest.

I'm not sure if that fish is bloated a bit though due to some sort of infection. I guess you could treat the tank with some general antibiotic or just hold on to see if there are any other fish affected.

Maybe someone else has experience of something similar and can advise?

 

[PrairieSunflower]

I googled around and found at least 2 other posts on two separate forums of the same sort of thing with black neons. In both cases the fish returned to normal after a few days to a week. Those forums didn't come to any definite conclusions on the actual issue.

 

[Gidge]

Thank you for all your speedy replies! I'll leave it for a little bit longer and see what happens. In the meantime I will try and get a picture of him/her next to the others for size comparison.