Any advice?

This is going to be a bit epic so I apologise, but if you make it through, any advice would be appreciated.

Tank has been set up and cycling for several months now. We have added fish gradually during that time and currently have 5 guppies, 4 corys, 6 neons, 2 platies and a female swordtail.

The tank is 100l.

Levels each week have been 0 ammonia, 0 nitrites, and 10-20 for nitrates. Ph has been stable too at 7.6.

We are currently trying to tackle an outbreak of brown diatoms and have added an API Phoszorb bag as we had high phosphates. This went in on Monday just gone.

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In late September we lost a female guppy. She became lethargic, went off food before ending up on her side nearly doubled over. Her fins also seemed a bit ragged around the edges.

Whilst she was going down hill we also had a bit of white poo from some of the other fish and saw some flashing. We used NTS antifluke and wormer medication for 2 weeks with decent water changes.

Since then poo has been more normal in colour and the flashing went away.

We added the 2 platies and the swordtail and had another couple of weeks of no issues.

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This week we noticed several of the livebearers flashing again.

One guppy (who has had fry just over a week ago - we took them out the tank) has a bit of a ragged tail fin compared to the others. Other than that she is absolutely fine. She is the bossy one so I wonder if the others have just been nipping a bit?

One cory is definitely unwell. He has always had a bent fin but was very feisty. Over the last week or so he's been sitting wedged in a plant and listing slightly before he'll swim off like normal. He doesnt seem to have grown like the other corys and seems paler in colour. He has still been eating. Today he was on his side and looked quite poorly so I have popped him in a floating plastic tub to keep an eye on him as our other tank has fry in it. He swims around for a few minutes then goes back to listing on his side. This is similar behaviour to the way the female guppy was before she died.

Levels remain as stated before. 25% water change on Monday and we added the Phoszorb. On Tuesday I dosed with the antifluke and wormer again as that seemed to deal with the flashing last time. I also took the carbon filter out.

As newbies to this, Im wondering if anything else could be wrong?

- Could the diatoms (or their dying off due to the Phoszorb) cause irritation?

- Have we just been unlucky with the guppy and cory and have purchased 2 weaker fish or could it be a bigger issue?

- Should I be concerned about the ragged tale on the female guppy?

The plan is to set up another tank asap to move the one adult male guppy into so we can eventually stop getting fry. We plan to keep any male fry and the females will go to the LFS. Im very wary of moving the adult guppy into a new tank though if he's potentially got something.

Help!

Can you post pictures of the sick fish and a short 20 second video clip of them flashing?

Can you post a picture of the diatoms/ algae?
Does the diatom/ algae wipe off easily and lift off in a film or sheet?
What does the algae smell like, musty, mouldy, or nice?

What are the ingredients in the anti-fluke wormer medication?

When you turn the lights off tonight, shine a torch on the fish and see if any of them have a gold sheen on their body or fins. If they do then they have Velvet (Oodinium) and that is why they are flashing/ rubbing on objects. Any whitespot medication will kill Velvet.

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Guppies from Asia are usually riddled with parasites and rarely last longer than 12 months in a tank. However, their young usually do well. There is a possibility the guppy is just weak and is going to die in the next month or so.
You should check the general hardness (GH) of the water. If the GH is less than 200ppm, then livebearers (guppies, mollies, swordtails and platies) will struggle.

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The Corydoras could have internal parasites but the dewormer should have dealt with them. Again it could be the fish is just weaker than its siblings and that is why it hasn't grown as much as the others.

If you didn't have Cories & Neons in the tank I would suggest adding a heap of salt and that will usually clear up most health issues in livebearers. But Neons & Cories aren't fond of salt. You could try low dose salt, see below, or move the Neons & Cories into another tank and salt the livebearers up.

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You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

If you only have guppies or livebearers in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and increase it after 48 hours if there is no improvement so there is a total of 4 heaped tablespoons of salt 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) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers.

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. Then do a 20% water change each day for a week. Then you can do bigger water changes after that.

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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.

There is a calculator/ converter in the "How To Tips" at the top of this page that will let you convert litres to gallons if you need it.

If you are using anti-fluke/ dewormer or any other medication, make sure you remove any carbon from the filter before treating or it will absorb the medication and stop it working.

Wipe the inside of the glass down, do a 75% water change and complete gravel clean. And clean the filter before treating. Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Increase surface turbulence/ aeration when using medications because they reduce the dissolved oxygen in the water.

Meds - flubendazole 100mg/100ml

Sick cory

Diatoms...

They are on the glass, back of tank, plant leaves, rocks and gravel.

It wipes off the glass easily but seems firmly stuck to the rocks.

Haven't smelt it and can't right now.

Didn't see any flashing last night and haven't spotted any yet today so no video of that.

The fish doing it were approaching the leaves and then flicking off them. They did this a couple of times before stopping.

Can't get a good picture of the female guppys ragged tale. It isn't torn...more like nibbled at the edges.

Thanks for all the information. I'll try the light thing tonight.

Aha..managed to get a reasonable picture of the guppy tail...

Flubendazole treats tapeworm and possibly some other intestinal worms but it won't do anything to external protozoan parasites, which are the most common cause of fish rubbing on objects.

Blue Green Algae (Cyanobacter bacteria) can irritate fish and cause them to rub on objects. This is most commonly seen in bottom dwelling fishes that come into contact with the blue green algae. If the brown stuff is algae and not Cyanobacteria, then it is unlikely to be the cause of the rubbing/ flashing.

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The female guppy appears to be in good shape even tho the edge of her tail is frayed. She does appear to be doing a stringy white poop that could be an indication of thread/ round worms, tapeworm or an internal protozoan infection.

If she is eating normally and has been doing a stringy white poop for more than a couple of weeks it is most likely intestinal worms.

If she is eating, losing weight and only been doing the stringy white poop for a week, then it is usually an internal protozoan infection.

If she stops eating, swells up, breathes heavily and sits just under the surface or near a filter outlet, and has only just started doing stringy white poop when those symptoms started, she has an internal bacterial infection and is going to die.

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The Corydoras sterbai looks awful. It is pale on the head and face and its fins are tattered. It might have Costia or another protozoan infection.

Thanks again. I'll do the torch test later to see if Velvet could be the issue and then go back to external parasites as I have seen the odd flssh in last hour or so.

Guppy wise...she gave birth to 9 fry the other week. All are fine. Her behaviour has been consistent sice we got her - swimming and eating normally, no weight loss. I haven't seen her flash at all and i cant remember seeing her poop recently so couldn't say if this white poo is new or not.

Cory...Im so upset as he is our favourite one. He's still on his side and breathing but has been swimming about periodically. I dont think he's got long left though by the looks of him. I'll look into costia as i havent heard of that before.

I am feeling really down as we had several weeks where everything seemed fine and I thought we were in a good place.

Costia, Trichodina, Chilodonella, Whitespot and Velvet are all external protozoan infections that can be treated the same way. Either heat (30C for 2 weeks) or use Malachite Green or Copper Sulphate.

Heat is the safest option but you should clean the tank and do a huge (75%) water change, complete gravel clean and clean the filter before increasing the temp. Increase surface turbulence/ aeration too to maximise the oxygen levels.

Copper Sulphate is safer than Malachite Green. Add copper to the tank and keep it there for 2 weeks and no more protozoans.
Copper will kill invertebrates like snails and shrimp so don't use copper if you have them.

Malachite Green kills protozoans but is also carcinogenic (causes cancer). Most whitespot remedies contain Malachite Green. If you use this stuff, avoid getting it on your skin and wash your hands and arms with soapy water after working in the tank.
Treat the tank for 2 weeks and no more protozoans.

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My preferred choice would be heat but the Cory might not survive the high temperature especially if you have to raise the temp more than 3C.

The tank is around 26 degrees C at the moment so it would be a decent jump for the cory. I think given how bad he looks we'll just have to take our chances.

We dont have any shrimp or snails so that's not an issue if we had to go down the meds route.

We have a spray bar so that can be angled to give more surface agitation.

I assume I can still dose for the wormer if I increase the heat?

We have plants in the tank, will the heat cause any problems with them?

We haven't done such a huge water change and clean with fish in...most has been 50% - any tips?

Spray bars don't provide enough surface turbulence for warm water. You want a couple of air stones bubbling away in addition to the spray bar.

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You can use the deworming medication in warm water but I don't think worms are a big issue here. Intestinal worms don't kill fish very quickly and most fish live with them for years before they get sick and die. And due to the condition of the Cory, I would not use dewormers in warm water just due to the extra stress that will be put on the fish.

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Plants and filter bacteria will be fine with the warmer water.

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Big water changes are fine for fish as long as the new water is free of chlorine/ chloramine before it is added to the tank.

Get a couple of big clean containers and fill them with water, add dechlorinator and aerate vigorously for 30 minutes. then use that water to fill the tank.

If it's a really big tank, use a water pump and some plastic hose to pump the water from the container/s into the tank.

Thank you