Fish dying

[Colin_T]

Your Nitrate should not be 0ppm. It should be over 6ppm and under 20 ppm at all times. When was the last time you tested for Nitrate?

You can have 0 nitrate in a cycled tank.

You want the nitrate as low as possible and kept under 20ppm at all times. If it sits on 0ppm, that is great.

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Checked nitrate tonight I have had tank running for several years. Gh is high about 70

GH is 70 ppm or 70 dGH?

For the OP, can we get some pictures of the sick fish?

What sort of filter do you have and what filter materials/ media do you have in it?
How often do you clean the filter and how do you clean it?

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Wipe the inside of the tank with a clean fish sponge.

Do a 75% water change and gravel clean the substrate every day for a week or until we identify the problem. This will dilute any disease organsims that might be in the tank.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks.

Then post pics of the fish.

 

[derikcalewell@tiscali.co.]

I have a separate GH test kit in tank its 71.6
Straight from tap its 35.0 (both ppm)

 

[derikcalewell@tiscali.co.]

Nitrate 5.5

 

[derikcalewell@tiscali.co.]

Fish

 

[Colin_T]

The molly is in bad shape. It's really skinny and could have internal parasites but they don't normally cause fish to sit on the bottom like that. The shop might have had them in harder water with a higher pH and the fish is stressed from that.

I would try adding some salt and then contact the shop and see what the pH and GH of the water is at the shop.

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 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 will affect some plants. The lower dose rate will not affect plants.

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.

 

[Essjay]

I have a separate GH test kit in tank its 71.6
Straight from tap its 35.0 (both ppm)

This is very soft water. Platies and mollies need hard water.

 

[derikcalewell@tiscali.co.]

What's best thing to do to up it?

 

[Aussie_Bristle]

My nitrate’s always sit at 0ppm, I’d be worried if it changed tbh

 

[Essjay]

You have tetras in the same tank and they are soft water fish. If you 'harden' the water for the liverbearers it will be too hard for the tetras. (And I missed that you also have swordtails, which also need hard water)
The two groups of fish, livebearers and tetras, have different hardness needs. There is no hardness level which will suit them both.

There are two solutions:
Decide which group of fish you want to keep and rehome the other. If you choose livebearers, you can make the water harder for them.
Or get another tank, separate the two groups, keep the tetras in soft water and harden the water for the livebearers.