Originally Posted by 1077
Water parameter's ARE the issue in my view.
While your ammonia and nitrites and nitrates are fine, you are attempting to keep hard water fish(guppies,mollies) in moderately hard water which WILL over time ,become moderately soft water which the guppies and mollies don't appreciate.(death)
You can medicate the fish till the cows come home ,but if fishes are stressed by unsuitable chemistry, the symptom's, deaths, will continue.
Do you not find it odd that the tetra's and cory's are not affected? It is possible that the water suits them, and hardness which the mollies and guppies need just isn't there.
If it is livebearer's you wish to keep, then I would consider setting up a tank just for them and might consider adding a 1/3 to 1/4 cup of crushed coral per 20 gal in a mesh bag to the filter and see if fishes (live bearer's) don't do better over the long haul.
You will need to clean or replace the crushed coral evey so often as it becomes coated with mulm,dirt,bacteria,etc while in the flow of water through the filterand becomes as a result,less effective
This method was the only way I was able to keep Lyretailed,High fin Swordtails, and mollies in my ALSO moderately hard water that became moderately soft after a few months.
First I want to say that I respect your view and thoughts, advice, opinions, ect.
I also want to add that I did lose cories, 2 habrosus (during the same time frame).
I am happy to say that since treating my tank for the fungus/bacteria, not only have my water parameters remained the same but not a single fish has died or appeared stressed.
As far as livebearers in hard water and not being put in any other water, I disagree. Here is why...
If they were wild caught, I'd be the first to say they need identical hard water caught from. Being tank bred over and over, they have a higher tolerance and ability to have a slight variation to this...plus they are very hardy fish. I dont think placing my guppies/mollies in mod hard water verses hard water is going to kill them during the amount of time that the ones that passed died (baring in mind that the 2 guppies that died were relatively new to the tank, the laserbeam about 3 weeks, and the endler cross (which is already a short lived fish) about 2 weeks).
I believe my livebearers are doing wonderfully and thriving. They have all grown nicely, their finnage is amazing, their colorations are vibrant, and they are active and healthy with no signs of any sort of stress one with an experienced eye would look for.
I could understand if I tried to keep them is very soft water, or in a cold temp tank, or some other extreme. But I dont think moderately hard water for hard water fish that were tank bred for generations will have hardly any if any impact at all on these guppies and molly. I plan on seeing the majority of them live for a total of 5+ years like these guys are expected to...heck, 4 of them are working on a year right now.