My guppies are swimming upside down, spiralling, their equilibrium is off.?

Question

My guppies are acting more strange than usual. I have a 20 gallon tank set up as a winter time haven for my small tropical fish. In summer they thrive in an outdoor pond. This particular aquarium has been set up for about 3 months now. The guppies are mixed in with many Mollies, also breeers and a few cordroy(?) catfish who are the tank janitors. There are fish in all developmental stages within the tank. I just cleared up a fungal infection with Melaffix, which worked great but my Guppies are now swimming erratically, either spiralling quickly, swimming upside down, "scraping" themselves on the bottom etc....It seems that the affected are starting this at maybe a month or 6 weeks of age and older. I do regular water changes. I feed live brine shrimp as a supplement. I have added "Shimmy blocks" within the last week to help condition the water, but ammonia levels and ph are kept under tight control anyway and the mollies and catfish seem fine. Help!

Answer 1

Sounds to me like your tank is overstocked and your fish are getting sick as a result.
A healthy tank with healthy fish will very rarely be afflicted by fungal infections or other diseases; these usually only manifest themselves in periods of stress or poor health.
How many fish do you have in that tank? If you have a few corydoras, you would also have room for only a few guppies and a few mollies. Maybe 5 of each. Anything more than that, and you're playing with fire. Mollies are surprisingly large fish and you need to take into account the fact that their adult size is 4".

Are they still eating or are they totally out of it? Move away from feeding brine shrimp. A day after brine shrimp hatch they are highly nutritious because they still have their yolk sacs. After that, they become far less nutritious, being mostly fat. It is unhealthy to feed a diet rich in brine shrimp - they are only suitable as a treat. If you want to supplement your flake diet, consider daphnia, bloodworms, mosquito larvae, cyclops, mysis shrimp...

As for treatment, start with a large water change, like 50%, and be sure to do 30-40% water change every week. Then, get rid of some of your fish. You didn't specify exactly how many you have but it sounds like you have too many. Restrict it to 4-5 guppies and 3-4 mollies. You could maybe add a couple more when your tank is healthy again, but that's the limit.
If you don't already, add a little salt to the water. Mollies like this anyway, and it'll help with all your fishes' immune systems. To your tank, add 4 flat tablespoons of aquarium salt, disolved first in dechlorinated water.
Feed them well, keep them warm, keep the water clean, and hopefully they will recover. There's not really any use treating them at this point because you can't pinpoint an exact disease, and general treatment can be more harmful than beneficial.

Answer 2

Sounds to me that you have WAY to many fish in your tank...

But from what you are telling us here it sounds like a bladder problem... Funny sounding yes....

Go here, http://guppyplace.tripod.com/Problems.html

Scroll down to #3 Symptoms look for the Behaviour part of the chart and read. Click on the links that it has and read.

I hope this helps.