Endlers bent back and paralyzed tail then dying

[jongalong]

Hey all. 
 

as the title implies I’m having issues with a tank where water parameters are fine temp is fine tank has been carefully cleaned but I’m having endlers who appear to be paralyzed at their tail and they develop a kink as shown below between dorsal and tail. 
 

any ideas what this is?

 

I’ve read pages of stuff online and in this forum and can’t figure out what it might be. 
 

can someone help identify the cause?

 

thank you!!

[Colu]

Bent or deformed spine can be caused by lack of minerals in your water what are your water parameters and have you added anything new to the tank resently and how long  have fish been showing symptoms 

[jongalong]

Thanks for the thoughts!
 

water parameters are:

ph : 8

nitrite : 0

ammonia : 0.25

phosphate: 0

nitrate: 0

gh: 5 drops

its been going on for a couple weeks and we’ve lost about 5 fish. 

I did a full tear down and 100% water change in the middle of this.

 
nothing new added to the tank. 

prior to this the tank was running gangbusters for about 2 years. 

[quikv6]

Hey jongalong,

I know you said water parameters are fine, but you are showing ammonia, and not showing nitrates....indicating something may have disrupted the cycle. That could certainly cause issues.

[Colu]

 you GH is on the low side for endlers i think it could be lack of minerals causing your problems what your kH at also in the mean time you could add some crushed coral to increase your GH or wonder shell

[jongalong]

Yeah we did another water change last night, and I will add some mineral content to increase the hardness a bit. 

I will check kH tonight as well.

Thank you again for the suggestions.

Edited January 20, 2022 by jongalong