Filters/Stress

Question
Hi Nicole,

I have a 20 gallon freshwater aquarium containing a family of black mollies. I recently bought a Marineland 150 filter for this tank, and I'm wondering what the ideal water level should be? Right now I have the water level about 4 or 5 inches below the filter...I thought this would be good for water circulation. I'm starting to wonder if this is too violent for the fish, and if it would cause stress.

Also, what is the absolute best diet/food varieties for black mollies?

Thanks for your time Nicole!

David

Answer
Hi David,

While I doubt it's particularly stressful for your fish, a lower water level like that is going to make headaches for you. You are probably going to see water spots on the glass, and the extra splashing will wet the underside of your hood. I personally keep my water level just at the bottom of the trim of my tank. I try to top it off daily, so that I won't have that annoying ring to clean later!

Lowering the water level does help when you are raising the temperature (for example, to treat ich) but unless you have decreased levels of dissolved oxygen, I would say it isn't necessary.

Mollies do like current, so a powerhead just below the surface or a bubble wall powered by an air pump would be appreciated, but it is optional. Your 150 gph filter is producing sufficient flow (150 gph divided by 20 gallons = 7.5x tank turnover per hour, recommended turnover is 6x per hour or more.) Maybe the best source of extra water circulation would be an air powered sponge filter:
http://www.aquariumguys.com/aquarium-sponge-filters.html
Which will eventually be a food source for very young fry.

The best diet for mollies is one high in fiber and low in protein, comprised mostly of algae and vegetable material. "Green flakes" (such as Omega One veggie flake, Spirulina flake) and algae wafers (I particularly like Omega One's algae wafer since the first ingredients are kelp and Spirulina) can make up the commercial, prepared foods diet. It is my philosophy that a 50% prepared foods diet is more than plenty of dried foods for fish, and the other 50% should be things like frozen food (daphnia, Spirulina enhanced brine shrimp) and fresh food like shelled, cooked peas, blanched spinach, zucchini, cucumber, etc. Mollies also like to pick at sheets of nori, which is roasted dried seaweed used to wrap sushi. I use a plastic clothespin to get it to sink, and most fish pick at it.

For more information on mollies and their care, check this out:
http://www.wetwebmedia.com/FWSubWebIndex/mollies.htm
It's probably the most thorough article on molly care on the WWW!

I hope that helps, take care.
Nicole