Molly's...is it just my tank?

[Olivia Letemplier]

Hey there,

I can't keep molly's alive in my tank! Is it just me? I was told that these are "hardy" fish but they don't last very long in my tank. Granted, my tank is not a pristine environment but my other fish are thriving. I have cichlids, long fin red minors, one spotted pleco, some neon tetras, swordtails and a bunch of platys. 55 gallon tank. Are molly's hard to care for?

[werehatwere]

I have a "Mollie guppy" 30 gallon tank, and they live just fine in there. However, I keep the water at a "Strong brackish" type and they love! The guppies are fine in there! I think the salt is helping them actually, because there very bright, active, and boy do I have A LOT of babies. I started with 2 guppies about a year ago, and so far, I still have the original 2, but have had to sell off about 200 full grown guppies. Ya they multiply a lot.

    Anyways for mollies, I have an issue with them. They like the water as well, and frequently breed. The only problem, is that after about 3 births, they unfortunately die, but leave me with about 150 fry each time. So every third batch (aprox) they get very slugish, and just pass away. I figured out that it was because they girls have no rest time before the males are back on them. So I set up a 10 gallon tank, for mom to spend about 3 days eating  lots of different types of food (Brine shrimp, boiled peas, flakes, blood worms...) until shes once again active and happy. This also makes her get a jump on starting the new batch. 

However, I find that mollies are hardy, in different categories. I mean that in terms of salinity, there good with almost anything. I know people who keep mollies in reef tanks. BUT in terms of space, they need it. One mollie needs at least 2 gallons in my opinion. That dosent mean that you can keep a single mollie in a 2 gallon tank. Feed em' vegies! My mollies were dying until I fed them veggies. The are very  herbivorous who LOVE lettuce.  It will also bring out there colour.

[Melody]

You hit the nail on the head, Olivia - Mollies require a pristine environment to thrive.  They need a regular water change schedule, gravel vac's, and good filtration.  They're your aquarium 'canary in a coal mine', letting you know when the environment is deteriorating.   They also need a healthy diet that includes more vegetation than your average omnivore.

It's also important to source your Mollies from reputable suppliers.  While there are certainly some fantastic retail sources, your odds are probably better with a private breeder in your area when it comes to Mollies.  A fish club meeting or auction is a great place to find them.

They're beautiful fish that are well worth the effort, and your other fish will also benefit from the increased maintenance.  Good luck!

[Fishnut]

The pristine environment is part of the equation but you also need to consider the amount of aquarium salt you're using.  The rest of the fish aren't the type you would see in a "brackish" tank but the mollies are.  Brackish water is essentially part way between fresh water and salt water.

Typically people add 1 TBSP of aquarium salt per 5 gallons of aquarium water as a tonic or help get rid of a disease.  Brackish water requires 1-2 TBSP of MARINE salt per 1 gallon of aquarium water.  Big difference! 

If you really like mollies, consider setting up a tank for them specifically.

Here's a pretty good website as a reference.  I haven't read the whole thing but the things I have read are accurate.  Scroll down to: Set-Up #2: Brackish River for your Molly set-up.

http://badmanstropicalfish.com/brackish/brackish.html

[Melody]

Salt isn't necessary if the tank maintenance is kept up.  Mollies can live in brackish tanks, but it isn't required.  Salt can offset less than ideal conditions and provide antimicrobial properties to a certain degree, but it doesn't address the problem directly.  I add a dash of seasalt (nowhere near the amount recommended on the box or for brackish conditions) for the minerals because my water is soft, but that's it.  

I've kept all sorts of wild-type Mollies (Sphenops, Petenensis, Velifera, Latipinna, etc.) and countless fancy domestic Mollies.  The only time I had a problem with them was years ago in one tank with an under-gravel filter.  I couldn't keep a Molly alive in that tank no matter what I did (including lots of salt).  Then I drained the tank to move it and found piles of sludge under the filter.  Mystery solved.  :-)

Livebearer expert Dr. Ted Coletti wrote an excellent article about Mollies in which he addresses the salt debate, The Fancy Molly.  In it, he uses one of my favorite quotes from Livebearer legend Dr. Joanne Norton:

"If water changes are large enough and frequent enough, and if all the water is well aerated and circulated, livebearers (all the species I have kept) do fine without salt added to the water. If these conditions are not met, or if the fish are too crowded, then troubles appear. Thus, salt enables you to continue one or more poor tank management practices that are still harmful even though the fish may survive them in the presence of salt..."

It is a common belief that Mollies need salt and it's in several hobby books, so I can understand why hobbyists still believe it's necessary.

[Fishnut]

So how do you explain how many molly species are FOUND in the wild in brackish conditions and how one of the best set of aquarium atlases published states in the description and care of "pet shop mollies" that they require a low level of salinity?  Baensch Aquarium Atlases were written by some pretty legendary fish experts.

This is not a simple matter of opinion. It's correct knowledge and published fact.  Mollies need salt.  Perhaps decades of inbreeding and forcing them to live in 100% fresh water has created fish that are capable of living in 100% freshwater conditions, and these fish have grown to be so sensitive that nothing but pristine waters is tolerated. 

It's great that you feel you have had success keeping them in fresh water but it is a practice that I feel is not the best practice to recommend.

[Melody]

Mollies are highly adaptable but they are not always found in water with measurable salinity.  They've been found in drainage ditches, soft water, etc.  I think if you read the information in Dr. Coletti's article you'll understand it more.  He quotes many people who specialize in Mollies and is a Livebearer author and columnist himself.  There isn't an expert alive who wouldn't bow to Dr. Norton's expertise on Livebearers.  She also founded the American Livebearer Association.

Information is often recycled in books.  One person says it's a fact, others use that as a reference and include it in their book, and so on.  They are also known to be ghost written by people who base the entire text on research, with no personal experience with the topic.  Of course, information is always updating in this hobby too, as further study is done and new discoveries are made.  Books are a great place to start for reliable information, but they're not infallible. 

However, it won't hurt Mollies to include salt.  The point is simply that they don't require it and their other requirements must be met for healthy fish.  :-)