Growth not responding to treatments

Can anyone tell me what is the white covering on this mollys head please? It was all white a few days ago but looks like a piece has flaked off. It's still swimming and eating but I'm concerned it's something which will impact the other fish. So far, none of the others have any. It's been like this for a few weeks now. I've tried water changes, parasite treatment, white spot treatment, raising temp slightly, and nothing has improved it.

I'm fairly new to fish so I'm worried about the whole talk dying off. Help!

It could be a fungus of some kind. I would put him in a quarantine tank by himself to make sure whatever he has does not get to the other fish. Even if it is not something that can spread, the other fish might pick on it and make it worse.

Rather than fungus, it looks like bacteria has eaten away at the tissue there. You need to quarantine and treat with antifungal/antibiotics (many meds treat for both). Kanaplex should work well in this situation.

What are the parameters at and what size is the tank plus the stocking? Often times disease is the results of poor water quality and stocking issues. If you could list the species of fish along with the nitrite, nitrate, and ammonia levels that would be perfect.

Hi, thanks for replying.
I'm not sure of the exact readings as someone else did the test. Nitrites are slightly above where they should be but all others are normal. (water change imminent in a few days anyway) Tank is 150litres and we currently have 4catfish (small) 1loach, 4 neons, 4gouramis, 1 cherry barb, and about 6 mollys. We have real plants and a decent filter (not sure what specifically but I was told it's plenty for the tank) and an air stone which bubbles away constantly.
Photo of tank below.

If there are nitrites then that is bad, this usually means the tank is not cycled. Any amount of nitrites will harm the fish, this could be your problem. You say a water change is going to be preformed in the next few days, I say do it now before further issues crop up. Water changes are good first aids for ill fish anyways. Clean water is vital to allow sick fish to recover.

Either way, I'd still separate the molly for treatment, I doubt it will recover on its own in the main tank. A 5gal (20L) bucket will work just fine so long as you have a spare heater and air stone. Whatever it has could be contagious and you do not want the other to become ill. Also, you won't have to use as much meds when treating a smaller amount of water.

Side note: what kind of loach and catfish do you have? Most loaches prefer to be in groups, as do cherry barbs and neons. A good number for schoaling fish is 6+, they will be far more active and ultimately more healthy when kept in larger groups.

Thanks.

It was actually a relative who stocked the tank for my daughter so I'm not 100% on what type. The cherry barb is the only survivor from the mini shoal we had in the smaller tank as are the neons. We had 8 neons. He seems to be fine shoaling with the neons. The loach has always been single. We had him in the old tank from about 4cm long. He's nearly 15cm now. Another photo below.

That is not a loach at all but rather a massive chinese algae eater. They can get pretty aggressive as they seem to prefer meatier foods as adults. Seems to be healthy but look out for aggressive behavior. I've had one that would chase any larger fish including gourami. Rotten thing was evil and had to be removed.

This one seems pretty shy. It's rare I can get a photo. He dug up most of the plants we'd put in the new tank and kept at it no matter how many times we replanted but that's the only "aggression" we've seen. I used to feed Daphnia but he never ate any. Loves the algae pellets I put in though.

UPDATE : So I think I found the source of the bacteria anyway... A molly had died and was lodged under one of the rocks at the back. Whether it died because it was caught or it just ended up there I don't know. It was covered in the same growth and most of its head was missing. Not the most pleasant...

So that is now two mollies with this bacterial or whatever it is? What are your water parameters, meaning the GH (general or total hardness) and pH? You have fish that need moderately hard or harder water (mollies) and fish that need softer water (tetras, catfish). There is no middle ground with these extremes, and mollies invariably get fungal/bacterial issues easily if the GH is not sufficient for their mineral needs.

The Chinese Algae Easter is also a prime suspect. I would remove it, it is not going to improve things as it matures, and it is as known eater of fish mucus layer.

This isn't the first tank we've had. We had a smaller tank with mollies, neons, the CAE and catfish previously for over a year with no issues like this. This is the first instance. Water source is the same. Only difference is the size of tank and the filter etc being used.

Belangaria said:

This isn't the first tank we've had. We had a smaller tank with mollies, neons, the CAE and catfish previously for over a year with no issues like this. This is the first instance. Water source is the same. Only difference is the size of tank and the filter etc being used.

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This does not follow; certain fish may be together for some time before issues suddenly break out in their behaviour. The initial tank was way too small for most of the mentioned fish, and changing tanks can affect the fish's behaviour. That is not saying that providing more and needed space causes aggression, but the cramped tank can permanently alter fish behaviours due to stress, and then the expanded space can trigger it. Bacterial issues can also be triggered by the tank space, and water conditions.

I am still thinking this is a water issue...what is the GH and pH? Without these we are not going to be able to offer anything further than what Demeter and I have; you need to provide the data to your doctor to diagnose, no different here.

I'll need to find out, as I don't know. But for the record, I only said the first tank was smaller. I didn't say how small, and I didn't have all the fish I mentioned yesterday in it. Having a larger tank, I added a few more. The first tank was 60ltr and it was certainly not overcrowded. We've had the new tank set up for 5 months now, and it was running for 3 weeks before we even put any fish in. They were transferred over the course of 6 weeks so not all at once. This issue can't be because of the setup or it would have surfaced before now surely? 3 months?
I'll try find out about the water hardness but I'm pretty sure ph is around 6.5.

Belangaria said:

I'll need to find out, as I don't know. But for the record, I only said the first tank was smaller. I didn't say how small, and I didn't have all the fish I mentioned yesterday in it. Having a larger tank, I added a few more. The first tank was 60ltr and it was certainly not overcrowded. We've had the new tank set up for 5 months now, and it was running for 3 weeks before we even put any fish in. They were transferred over the course of 6 weeks so not all at once. This issue can't be because of the setup or it would have surfaced before now surely? 3 months?
I'll try find out about the water hardness but I'm pretty sure ph is around 6.5.

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As I said previously, an issue can be fomenting for weeks, even months, before something suddenly triggers it. As an example, it is believed that ich (white spot parasite) is present in most all aquaria, yet fish do not succumb; but severely stress them suddenly as for example if the heater fails during a cold night, and ich breaks out. This is why tank size, water conditions, maintenance, suitable fish species in suitable numbers, etc are all so very important right from day one. Fish grow continually, both externally and internally, and all sorts oof factors affect them. Life in water is completely different and much more interactive than on land.

You may be able to ascertain the GH from the website of your municipal water authority. There is no need to acquire a test kit you may only use once, so track them down. I am however even more convinced this is a water issue; a pH below 7 is acidic, and mollies absolutely cannot function well in acidic water. If the GH is on the soft side as one would expect from an acidic pH, this is almost certainly the source of the problem. And the fact that it is affecting mollies only suggests the same. But the GH will pin this down.