Molly, erratic swimming/seizure?


I need help ASAP! :(
What is the water volume of the tank? 5 gallons
How long has the tank been running? Without the fish-1 month. with the fish-4-5 hrs
Does it have a filter? Yes
Does it have a heater? Yes
What is the water temperature? 75-80 degrees
What is the entire stocking of this tank? 1 silver molly 1 black molly 1 octolus catfish.

How often do you change the water? 1 time a week.
How much of the water do you change? One time before I got fish I did a 100 percent water change, but usually 50 percent
What do you use to treat your water? Topfin water conditioner, top fin ammonia neutralizer, and PH up.
Do you vacuum the substrate or just the water? Neither yet.

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes. For a month.
What do you use to test the water? API Freshwater master kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0
Nitrite: 0
Nitrate: 5.0
pH: 6.0

How often do you feed your fish? Just once this evening
How much do you feed your fish? A pinch
What brand of food do you feed your fish? Omega one freshwater flakes
Do you feed frozen? No
Do you feed freeze-dried foods? I don't think so

Illness & Symptoms
How long have you had this fish? 4-5 hrs
How long ago did you first notice these symptoms? 1hr
In a few words, can you explain the symptoms? My black molly has been acting weird, it looks like a seizure or having a hard time swimming. I did some research and I think it might have the swimmies.
Have you started any treatment for the illness? I have tested the water, nothing else.
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? Now it is not moving around much and acting lethargic.

Explain your emergency situation in detail.
I got my Mollies and catfish a little while ago. Water levels were perfect. I fed them a little bit and they were swimming around fine. I then noticed my black molly swimming frantically. I did some research and it may have the swimmies. I since tested the water (test results above) and found that the PH had drastically dropped from 7.0 this morning (before I got them) to 6.0 now. Now all of my fish are laying at the bottom and not really swimming around. I didn't add anything to the tank except food and a little algae tab for the catfish since I don't have algae in my tank yet. I don't really know what to do. It took me a month to get the ammonia and PH levels good enough. A water change I feel will spike the levels even worse like it did before. Is there anything I can do?


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Welcome to Fishlore.

The problems are the tank is overstocked and the pH is still too low. Mollies prefer a pH of 7.5-8.5 (as with other livebearers) and they’re, to an extent, brackish water fish. In the wild they occur in estuaries. There’s nothing to suggest why the pH dropped to 6.0 in your message but mollies are messy fish that poo a lot, and breakdown of organic material can lower pH. When I was cycling tanks using flake food I discovered that the excess flake was causing the pH to drop, so I went ahead and tacked that.

Mollies fight each other. They exhibit territorial behaviour and in a 5 gallon aquarium there’s not enough space for them to make territories. They’re not going to share it, meaning they will fight each other for top place in the hierarchy. Chances are they’re stressed and settling in for now, but the setup is inadequate for mollies and problems are more than likely to occur down the road.

I would be worried about the otocinclus catfish because they feed on microfauna that take time to develop in an aquarium. The term for these microfauna is “aufwuchs.” After only a month of setup there likely won’t be enough aufwuchs in the tank to feed the otocinclus for long. Otos will often starve before they can recognise commercial foods as food. They’re troublesome fish...

Doing 100% water changes has a chance to give the fish osmotic shock, which is usually fatal. I like how you’re now doing 50% weekly and that’s what I do. I use Seachem Prime as my dechlorinator.

Also, I‘m a little confused; your aquarium details says you don’t know what the cycle is, even though you mention cycling the tank? Did you use an ammonia source and monitor the mg/L of ammonia, nitrite and nitrate for that month, using your API Master?

Edit: I just realised you’re using pH up. Don’t use pH products. Chasing pH is hopeless and will do more harm to the fish than good. Same with that ammonia neutraliser. Just use fish that are suited to that pH rather than chasing a higher pH.
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I hope that the aquarium in the photo's is not the one that you have Otto's or any other fish living full time.

No plants, no ornaments, no Otto grazes aufwuchs that is found on plants, ornaments and rocks, it takes a while to get to the right levels so its never a good idea to have Otto's in an unestablished/uncycled aquarium cos they will surely starve to death unless fed supplemental foods.

Fish need places to hide, places to chill out and relax....a naked aquarium doesn't do any of that.
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Hello. StinkyLoaf (I love that username)
Let me answer some of the above questions. I don't know why my PH dropped. It was very sudden and the PH was around 7-7.5 before I got them. But your information helped me figure out the probable cause.

As far as the mollies fighting each other, I made sure they were already in the same tank previously before I got them. They have already been together.

The space, I do have a 10 gallon tank that I was planning on upgrading if it was too small for them, but everything I read said an inch and a half of water per inch of fish. So I thought I It was enough room but maybe not! :) I will think about upgrading the tank.

The 100% water change was way before I had the fish. I'm only doing a 50% water change now.

I don’t know what the cycle is, because I don't really understand the question?
But I did Did monitor the ammonia, nitrite and nitrate for that month, using my API Master. I did it once a week. (sometimes more)

Thank you for your help! :)

Hi pagoda.
The aquarium in the photo is it. I had purchased some rocks and ornaments but they were too big for my tank and am going to get more. I thought they might be ok for a day without them. I had live plants at one point but I know nothing about them and they seemed to be making the ammonia spike (when I was testing the water before I got them)

I'm not quite sure what you mean by I cycled I have been cycling the water for a month to get the water levels to where they need to be and they were fine this morning before the PH dropped what seems randomly and rapidly.

Thank you for your help! :)
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My username, yeah... based on my cats. :)

I have some stocking advice for you. First, the inch per gallon rule (and other similar “rules”) is bogus and has failed many hobbyists. A 50 inch long fish won’t even fit in a 50 gallon for example. I recommend a 30 gallon tank for a small to medium size group of mollies. You’ll see many people advise you keep a minimum of six fish per shoal, but honestly, the fish aren’t going to do math and calculate how many there are. A group of five fish will act the same as a group of six fish. Keeping mollies in a male to female ratio of 1:3 is advised though.

Even if the mollies are from the same tank at the shop, changes to their environment can cause territorial behaviour to occur. If they’re removed from their original hierarchy they’ll make their own, and the original hierarchy will also change. Territorial fish are unpredictable like this.
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That makes sense. I always thought it didn't add up but I was reading that rule everywhere so I thought they were right.

I also thought that since I was new maybe two would be ok. Is it still possible to have a 10 gallon tank and do 2 Millie's or should I use a 30 gallon tank and get 5 just to be safe? I know I don't know what I'm doing and I don't wanna get to many and fail them :(

Is there anything to prevent them from being territorial? Will that be solved with more room in the tank?

Again, thank you so much. This has been a HUGE help. :)
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A 30 gallon minimum with at least four mollies so there’s a male to female ratio of 1:3. Add lots of hiding places using plants, rocks and driftwood so territories can be discerned by the fish. This is the best way to relieve territorial behaviour in fish.

Driftwood won’t soften the water or lower the pH unless the water has a low carbonate hardness (KH). Mollies are hard water fish and there are certain rocks, such as limestone, which can harden water and raise pH, usually to what mollies prefer. Rinse rocks under warm water before use (don’t cook them!) and avoid using rocks you find in the wild because they often contain small critters.

Expect lots of breeding and for the females to be perpetually pregnant. You might end up with some fry, but raising every fry you see will result in a need for more tanks to accommodate them. Most will get eaten by the parents.
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Awesome! Thank you so much. :)
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