Two unhappy Mollies in 70 gallon tank

I have a 70 gallon planted tank that’s been running about two years. It’s lightly stocked with a school of 15 rummynose tetras, a clown pleco, 12 Julii and albino Corys, and a bunch of yellow shrimp. My canister filter is rated for 150 gallons.

I originally had four very active gold and black mollies…but one day out of the blue, two got dropsy and died. They were about two years old. I did a full water change and cleaned out my canister filter. I did not test my water to find out what happened, just immediately did a water change. (And I wish I tested first) No other fish were affected.

However, since then (it’s been about six months) the two remaining mollies are constantly hiding, very shy, and always laying on the bottom under rocks. They come out to eat when I feed and act normal when there’s food….but otherwise their behavior has really changed.

I thought maybe they were lonely, since my water parameters are normal and my tank is pretty mature and well-maintained….so I bought four more mollies (two black lyre tails and two koi-lookin’ ones). The new mollies all school together and are social and active. My two old gold and black mollies….do not interact with them, nor did it help coax them out of their depressed hiding.

So my question is: Do mollies become less social when they age? Is 2-years considered old for a Molly? Do they mourn the loss of their two homies? My LFS told me mollies will school with other colored mollies…is that true? Why would their behavior completely change after whatever happened in my tank six months ago and why have they not bounced back?

Thanks a million, fish fam.

 

I don't have much experience with mollies but I think they should live around 3 years. Mollies need hard water and I believe can benefit from salt added to the aquarium. But your other fish are softwater species - perhaps your water is more suited to these soft water fish - do you know your pH and hardness?

 

I don't have much experience with mollies but I think they should live around 3 years. Mollies need hard water and I believe can benefit from salt added to the aquarium. But your other fish are software species - perhaps your water is more suited to these soft water fish - do you know your pH and hardness?

I definitely have hard water, but my LFS told me they have hard water too (it’s the city water, it’s all hard lol) so all the fish in his store are conditioned to harder water. It seems to be just those two old mollies affected, as the other four newer ones (and all the other fish in my tank) are perfectly healthy and active. I know their life expectancy is around three years…mine are not three yet, but maybe they’re just slowing down??

Thank you for your reply!

 

I definitely have hard water, but my LFS told me they have hard water too (it’s the city water, it’s all hard lol) so all the fish in his store are conditioned to harder water. It seems to be just those two old mollies affected, as the other four newer ones (and all the other fish in my tank) are perfectly healthy and active. I know their life expectancy is around three years…mine are not three yet, but maybe they’re just slowing down??

Thank you for your reply!

Could be, and maybe they were not juveniles when you got them...

 

Could be, and maybe they were not juveniles when you got them...

True. Sigh. My senior citizen Mollies.

 

Frankly, I don't know much about mollies as they've only been transients in my tanks, but I wonder what gender mollies you have? Do you keep to all male or all female? There may be an issue with gender numbers if you've kept them mixed & the ratio is off with the new guys.

But my ulterior motive after giving that mild suggestion is to comment on your tank. It's unusual & eye catching & I decided I love it after getting a good look at your alien. The alien perspective on x-files! Thanks for the laugh.

Hope your black mollies eventually come out to play.