New Member
Jul 20, 2016
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So I currently have only one fish in a 25-30 gallon tank of brackish water. He's a silver Molly with black spots named Rorik, and ever since his mom died, he's been alone. As a social fish, I worry about him, so I've been thinking about getting him a few tank mates. I'm trying to be careful, one new fish at a time, and I was thinking about getting a female Betta as his first tank mate in several months. Now I've heard that female Betta are fine with nonagressive Mollies. The temperature of the tank seems just right, the water is in nice condition, but what worries me is Rorik himself. He's been alone for so long, he may be a little too used to being that way. I dont plan on getting any other Mollies, because I really don't want a mic up that would result in a plethora of fry. But can anyone suggest other fish to put in with him? Can I put in a female Betta now, or should I wait until after there are a few other fish? Can I start with a baby female Betta, will it help with her temperament if she's exposed to other fish at a young age? There is room to hide, a large log with multiple exits. I have so many questions, thank you to all who answer!


Fish Expert
Feb 25, 2009
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If you retain brackish water, you will not be able to add any freshwater fish species aside from more mollies.  While mollies can manage in brackish water (though they do not require it to be healthy), other freshwater fish cannot.
A 25-30 gallon tank is not all that much space, and mollies are not small fish--males attain 3 inches, females 5 inches and some have reported 6 inches.  To avoid fry (and that is a genuine concern) stay with all males; you could add another couple male mollies (different varieties will provide interest, or stay with the same you have, up to you).
I am assuming your source water is moderately hard or harder in GH.  This is essential for mollies as they will not do well without the "hard" minerals, calcium and magnesium especially.  Many think salt replaces these, but it does not; salt is a mineral in its own right, sodium chloride, but it is the calcium and magnesium that mollies need to be healthy.  Unless there is another reason you need brackish water here, I would consider returning to freshwater (over several water changes) and adding some plants which are appreciated by mollies.
The Betta is a soft water fish, and not suitable for mollies as the water will be harder than Betta prefer.


Fish Herder
Tank of the Month!
Oct 28, 2014
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Carnoustie, Scotland
What about some male guppies? I think you could gradually reduce the salt to a level where both fish would be comfortable.
I'm not certain of this though as apart from when I first started keeping fish, I haven't kept either.
It is fairly easy to sex mollies so maybe some more males?


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