Neon Tetra With White Spot On His Mouth

Hi @Eduh and welcome to the forum

I'd advise monitoring/watching carefully to see if the situation develops beyond that. If it's just the one small white spot, it might not be anything of concern - I have a neon green rasbora who's had a white spot on her lip 80% of the time throughout the 18 months since I've had her but it's never developed beyond that.

If the situation develops into lots of white dots like salt or sugar grains, then it would likely be whitespot - details here of how to treat that. https://forums.thinkfish.co.uk/fish-medicines/medicines-for-treating-different-conditions/

If the spot seems to develop or get worse, or any other symptoms appear, then it might indeed be cottonmouth/columnaris and require treatment with eSHa 2000 at that stage for bacterial infection.

On a more general nature:
* I see you're keeping hard-water fish (mollies, platies) and soft-water fish (neon tetras). It's unlikely that your water will favour both, and more likely that some species will thrive and the others will succumb to various conditions. Check your water supplier's website, for your postcode, and find out what your water hardness level is in CaCO3 and German degrees hardness, and that will help work out which fish are likely to do better and/or if we can advise on how to help you achieve that.
* Are the mollies and platies all male? If not, have you decided on your plans if they start producing multiple offspring, repeatedly? Again, we can help advise on potential options.
* Long-term, mollies generally need 90cm / 3ft tanks, so it may be worth considering an upgrade of size of tank when you're in a position to do so.

Hope this is helpful. 

Hi @Eduh

Welcome to ThinkFish!

Firstly, your questions. The preferred GH range for Neon Tetras is 1dH -5dH. For Mollies and Platies, it's 11dH - 30dH.  Your Neons will probably be OK but the water is too soft for Mollies and Platies. The KH is fine.

How did you cycle your tank before adding the fish?

I see that nitrite (NO₂^-) is 0.1 ppm. This is too high. You need to keep this at 0 ppm. In other words, the lowest marker on your JBL Test Kit.

As for uploading photos, you need to locate the photos on your phone. Is it iPhone or Android? Once you've found your photos, you can use the 'share' facility.

JPC

This site will low you to convert the images to the required format (it’s what I use with my iPhone) https://image.online-convert.com/convert-to-jpg

It’s likely your nitrite is fine and some people never see the true zero colour due to lighting etc. How old is the tank?

I would get the neons in good health before you consider adjusting your water parameters as they favour them currently.

Yep I think the plan outlined above is right... maintain excellent water quality to help the fish along during its recovery... up your water changes to 50% twice a week would be my suggestion