Reasons for gauntness in guppies?

[PineSong]

(Tank parameters in photo below)

I noticed 2-3 weeks ago when I was renovating my 20g tall that  a couple of guppies were quite thin. Both of the gaunt females were born here, to mom fish who had been through my QT process of 2 doses of Paracleanse and 2 doses of Expel-P. Instead of having a curved belly, their bellies were straight on the bottom and what I call slab-sided. No roundness to them. One of them has since passed away, and she was only about 9 months old.

Today I was trying to count fish in my 20g long, which has male guppies. One of my male ginga sulphureus guppies now looks gaunt, too. He was purchased on Aquabid summer of 2021 and also went through QT here. The other male who arrived with him is still alive and normal plumpness. In the photo, the bottom fish is the thin one. Notice the bottom line of his body is a straight line. 

Other fish in these tanks look normal. Both tanks are heavily planted but overstocked due to fry situations I am resolving by selling/giving away juveniles. The 20g tall I removed the heater from a few weeks ago, the 20g long I removed the heater from a few days ago. Now I am wondering whether that's a problem. House is kept in mid 70's by day and low 70's by night.

My questions: what can cause gauntness other than parasites? Should I just dose both tanks with paracleanse and/or expel-P or both (not at the same time) and treat it as an annual deworming as with cats, dogs, horses, etc? Anything else I should do or consider? thank you.

 

 

[Colu]

Are they eating ok and still losing weight also have you resently had any ammonia or nitrites spikes

[PineSong]

On 5/18/2022 at 9:21 PM, Colu said:

Are they eating ok and still losing weight also have you resently had any ammonia or nitrites spikes

I went to feed them because you asked and yes, they go after food vigorously. I am not aware of any spikes, I use test strips at least a couple of times per week per tank, but I don't normally test for ammonia anymore. The nitrates shown on that strip are the result of fertilizing 2x per week as otherwise I have no nitrates and I'm trying to keep them there for the plants.

Prior to my renovation of the female guppy tank a few weeks ago, it was dark from wood tannins,quite infested with hair algae and was pretty dirty, to be honest. I had avoided cleaning the filter because I didn't want to hurt the shrimp I had just added, and I think I went too far. So it could have had ammonia spikes from overpopulation, dead fish I did not see due to plants/tannins prior to cleaning. The other tank has never been dark or looked that dirty, but it has been overpopulated with platy fry/juveniles for at least three months.

[Colu]

It's possible you suffered an ammonia spike it's difficult to no for sure if they eating ok and still losing weight I would do a course of Expel p just in case your dealing with wasting disease it's really common in livebearers

[PineSong]

Thank you, @Colu, I will.