I have a new 10 gallon tank (3 weeks old). When I setup the tank I added two guppies and a bottle of Tetra Safestart. I never saw Ammonia rise above 0.25ppm, and it dropped to 0 after 2 weeks. One week ago I added the yellow guppy (se pics below)
Ammonia, NItrite and Nitrate are all 0ppm. PH is 7.6. I have never seen any nitrite or nitrate in the tank, but my bioload is light enough that they might just not be detectable in between the weekly 30% water changes. For now I am assuming that the tank is cycled since Ammonia has been at 0 for more than a week.
I have three male guppies, but one of the guppies (the yellow one) is a little chunky and has a body shape like a female. All three fish have a gonopodium so I am sure they are all male. I have a attached a photo so that someone can double check the sex.
Two of my guppies are constantly chasing the yellow guppy to the point where I am starting to worry about it. The yellow fish seems a little stressed.
The blue guppy seems to be showing what to me looks like mating behavior. It will arch its body, flare its tail and shake its whole body. Both the blue and red guppy also keep chasing the yellow fish and seem to be biting it in the gill area.
I tried to capture the behavior in a video here:
Guppies - YouTube
So my questions are:
1. Is the yellow fish a male?
2. Is the body shape of the yellow fish triggering mating behavior in the other fish?
3. Is it normal for the yellow guppy to be so fat, or is this a sign of dropsy or some other problem? The fish seems OK and it eats like a piggy. The yellow fish eats 90% of the food at feeding time, so I think that it is just chubby.
4. Anything I can do to help out the yellow fish? Would adding more fish help or hurt?
Thank you for your help.