mollies 150x150 My Favorite Article on Molly FishI run into people having troubles with mollies all the time.  Also you hear the debate on whether or not mollies need salt or not. I often refer my customers to an article on wet web media. We would like to share it with all of you guys also as it explains a lot of misconceptions. It’s a little wordy and thorough, but you’ll be a molly expert by the end of it.

The Truth About Mollies


So pulling all these issues and observations together, it is obviously that mollies are much more demanding fish than most aquarists assume. But the key things to get right can be summarised fairly easily: All mollies need very clean water with no nitrite and as little nitrate as possible. The water needs to be warm, and hard, alkaline. Most aquaria are slightly too cool for mollies to really thrive, and the soft and acidic water the majority of aquarium fish enjoy is positively harmful to mollies over the long term. The addition of marine salt mix isn’t essential — but it will offset any lapses in water quality management and will raise the pH and hardness levels to where they should be. Table salt, or tonic salt, is perhaps better than nothing, but because it contains nothing to harden the water, it is far inferior to marine salt mix in terms of benefits. If you’re going to add salt, the exact amount doesn’t matter because mollies will accept anything from freshwater to full strength seawater, but in terms of benefits against cost, aiming for 20% seawater (SG 1.004) would be about right. At this salinity, your freshwater-adapted filter bacteria will not be harmed, and the amount of salt needed would not be very great, about 7.5g/l (1oz/gallon).

All this would seem to make mollies incompatible with community tropicals, and to some extent that is true. But, although things like tetras and Corydorasprobably don’t have any place in the molly aquarium, there are plenty of fishes that will thrive in the warm, hard, alkaline water these fish need. Almost all of the New World livebearers enjoy these conditions, and most will even tolerate small amounts of salt if necessary. Other freshwater fishes tolerant of such conditions include glassfish and wrestling halfbeaks. At SG 1.004, a nice variety of unusual brackish water fishes could be kept as well, including bumblebee gobies, Brachirus sp. soles, and orange chromides. The violet goby Gobioides broussonnetii would be an especially interesting addition, coming from the same parts of the world as the mollies and inhabiting the same sorts of waters.

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