Mollies Dying

[CinnamonPearl]

Recently in my 38gal brackish tank, I've had a couple of saddening deaths with my black mollies. Could anyone help me figure out the reason for these deaths so I can save my remaining three mollies? So far, the deaths have been identical to each other. What happens to my mollies is they'll start to experience what looks like losing scales around the face, so their faces will look grayer instead of jet black. Then I'll see that they're missing huge chunks of their tails, as if they were torn off. It doesn't look like fin rot, it looks more like an injury. And two days after that, I'll find them dead. This has happened to two of my mollies so far, one after the other. Does anyone know what could be causing it? Thank you.

 

[FreshyFresh]

What's your water change schedule and amount changed?

 

[tanker]

Are the Mollies the only fish in the tank?

 

[CinnamonPearl]

I change about 30-40% of the water every other week, but I sometimes do smaller changes in between when I can. There are currently three mollies in the tank along with three knight gobies.

 

[tanker]

Your knight gobies are your problem.
1) They are semi nocturnal, so they "Like" to come out later in day (lower light).
2) They are very territorial, and will attack other fishes--Your mollies.
3) They are know fin nippers-- Your mollies.

 

[CinnamonPearl]

Oh goodness, I had no idea! Of all the time I was reading up about knight gobies, all I heard is that they would eat small fish. There really is no word out there about their being territorial. What do you think I should do? Would the better plan be to rehome the gobies and try to find some other brackish fish compatible with mollies? Or if I rehomed the mollies, would the gobies be okay if I got a few more of them and just made it a species tank, or would they not handle that well?

 

[tanker]

Knight Gobies are territorial not just to other fishes, but to themselves too. They are much better by themselves, or even better, by themself.

 

[CinnamonPearl]

Okay, the knight gobies will be rehomed. It's such a shame, I really did like them. Do you happen to know any other good brackish fish I can keep with mollies? The only ones I know of are bumblebee gobies, but I've heard they're difficult to keep and require live foods. Honestly, if I can't find any good brackish fish, I might just throw in the towel and go back to freshwater.

 

[tanker]

Orange or Green Chromides?

 

[CinnamonPearl]

I looked into orange chromides back when I was planning stock, but it turned out that they eat plants, and I couldn't find any for sale anyway. Do you know if green chromides also eat plants? If not, I'll look into them.