Platy Headstanding

Question
I have a 29 gallon tank with a biofilter, bubbler, pebble bottome and fake plants. It's stocked with 7 adult platies, 15+ baby platies (will be giving away!), 6 zebra danios, and 4 cory cats.  All my water testings show 0 on amonia and nitrite, 30-40 on nitrates.  I do a 25-40% water change every other week, or inbetween if my 0's creep up (rarely needed).  My water is crystal clear 99% of the time. One of my momma platies has a big tummy and has been head standing near the top of the tank for the last week. She still eats, and will go to the bottom of the tank to eat some of the sinking food I use for my cories.  The last couple of days her tail fin has looked limp when in a head stand, although it does look 'normal' when she swims (still swims vigorously).  Her scales are not 'puffed'.  She's given birth several times in the past 2 months.  Should I isolate her and withhold food? Or.....??

Answer
Hi Janice,

I would switch to weekly water changes of 25-30%. If you can't manage that, then 50% every two weeks is ok, but it's better to change water weekly. Livebearers love hard water, and when you let the water get "old" it tends to chip away at the alkalinity, which has a bearing on pH. Keeping the water fresher is best, and it dilutes high nitrates.

You might be overfeeding a tad, sometimes sinking pellets can be very polluting. Especially if you have a pebble bottom (rather than sand or very fine gravel). Here's what I would do - vacuum the gravel deeply. You'd be surprised how much junk is in there! Do a 25% water change. Check your alkalinity, and pH. If any of these levels are "low" then you know you will need weekly water changes. It might also help to add a homemade salt mixture with your weekly water changes. 1 teaspoon of Epsom salt, 1 teaspoon of sea salt, 1 teaspoon of baking soda mixed together will treat 5 gallons of water. This recipe is called "Malawi salt mix" (aka "Rift Valley cichlid mix") and is used for African cichlids, who love hard water...but it's very beneficial for goldfish and livebearers, as well.

To recap:

1) Vacuum the gravel (it will bring your nitrates down)
2) Change 25-30% of the water weekly, if you can
3) If your pH and alkalinity are low, use the salt mix to bring up those levels

I've never heard of platies head standing, but tiger barbs do it when nitrates are high. So give these suggestions a try!

Another thing to do is to feed your fish shelled peas instead of sinking pellets sometimes. Take a frozen pea, defrost it, and pinch the skin off. You'll find your platies and corydoras both really like this food! I also find that a strip of nori, which is roasted seaweed used to make sushi, weighed down with a plastic clothespin gives the fish something to nibble at. Both these foods are high in fiber, low in protein so will not pollute your tank - and will keep their intestines clean. Green foods (algae and vegetable based) are very important for healthy livebearers! You can learn more by reading this article:
http://www.wetwebmedia.com/ca/volume_4/v4i3/Livebearers/Livebearers.htm

I hope that helps, take care!
Nicole

P.S. Do not isolate your female platy unless she starts showing signs of fungus, finrot or other more serious ailments (then medicate with a suitable antibiotic, such as Maracyn)...upping the water quality, feeding green foods should do the trick here.