Issues with my 2 Black Mollys

HI All

In my 190L fluval tank I have 7 mollies and 2 Plecos.

4 of the fish are fine as seen in 20200915_171818

The All White Molly has spent alot of time on the surface for the last couple of weeks. - I assume this is because she looks pregnant. pic: 20200915_171829

My worry is the 2 black mollys. Shown in the other 2 pictures.
In pic: 20200915_171850 its hard to see but hes on his side. I thought he had died a couple of times today but as I went to move him he swims away.

With the other one (pic: 20200915_171836) hes not doing it as often but again is starting to do similar things. I didn't feed them last night but it hasn't seemed to have helped.

I am aware the male to female ratio is slightly off as I have 3 males and 4 females currently but these 2 look distressed

All fish have been in the same tank a for a couple of months but nothing has been added.

In the last 3 weeks we have had 2 bouts of Ick but it was on the orange fish. Due to this in the last 3 weeks I have done 2 40% water changes.

Pic: 20200915_173840 is one of the black mollies swimming.

Any thoughts?

Thanks
Chris

Finally got a good picture. Thoughts?

Soft water, low pH, poor water quality, intestinal worms, gill flukes and maybe some external protozoan infections.

Check the ammonia, nitrite, nitrate, pH and GH of the tank water.
Mollies need a pH above 7.0 and a GH above 250ppm.
Plecos come from water with a pH below 7.0 and a GH below 100ppm.
Having the 2 species together is always going to be an issue. If the water is too soft the mollies suffer. If the water is too hard the plecos suffer.

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Add some salt.
You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres (5 gallons) of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate will not affect plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

Thanks. I have done a water test using the tetra strips and it seems OK?

NO3 is getting to the point of a waterchange but not awful
NO2 almost none
GH is 8d
KH is between 3d and 6d
PH is between 7 and 7.6
CL2 also OK.

They have been in the tank for months without salt so am slightly surprised they would need any now but worth a shot.

Is it teaspoons on tablespoons? 19 tablespoons of salt seems alot (190L tank).

I also do not have a quarantine tank. I am worried that adding the would salt affect all the other fish who all seem OK.

I have noticed that the orange male seems to be the alfa and is picking on the other 2 males. This is more so now I lost 2 females due to age a few weeks ago. Which isn't a surprise.

I have put one of the black mollies separate in what is a birthing cage and hes been on his side all day so seems a matter of time before he goes sadly.

The other is swimming around more and seems normal around 80% of the time which is odd.

NO3 is getting to the point of a waterchange but not awful
NO2 almost none

We need actual numbers please.

ETA: Ammonia reading?

Anything above 0 - even slightly above needs a water change as it can cause lasting damage

The GH is too low, it's around 150ppm and needs to be a bit higher.

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Tablespoons for salt.
And yes it seems like a lot but is safe for the fish.

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Before you treat the tank, do the following things.

Do a 75% water change and gravel clean the substrate. Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

To work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.
When you measure the height, measure from the top of the substrate to the top of the water level.

You can use a permanent marker to draw a line on the tank at the water level and put down how many litres are in the tank at that level.

There is a calculator/ converter in the "FishForum.net Calculator" under "Useful Links" at the bottom of this page that will let you convert litres to gallons if you need it.

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Stacker123 said:

I have noticed that the orange male seems to be the alfa and is picking on the other 2 males. This is more so now I lost 2 females due to age a few weeks ago. Which isn't a surprise.

Click to expand...

That is normal behaviour with livebearers having a pecking order with a dominant fish bullying weaker fish to keep its position. Adding or removing fish will cause fighting until the pecking order is sorted out.

Thanks guys. As I have mentioned I have done 2 40% water changes in 3 weeks. But will do another at the weekend when I have time.

I use the to test the water so i cannot give exact numbers.
https://www.amazon.co.uk/gp/product/B001B65ZVQ/?tag=

I will get some salt add some when I do the water change. Is there a type you would suggest?

Nitrate should not be used as the indicator that a water changes needs to be done. Water changes should be at least 50% every week regardless of nitrate levels. 2 x 40% water changes in 3 weeks is not enough, I'm afraid.

You don't give the nitrate level but it should be less than 20 ppm at all times, including just before a water change.