Help! Everything in my tank keeps dying after getting cardinal tetras (TW - Dead fish pic)

[Byron]

Unfortunately the OP is in the UK and metronidazole is not available here without a prescription. A vet may be willing to supply a prescription, though there aren't many that deal with fish.

Is the Seachem MetroPlex not available in fish stores that carry Seachem products? Or can it be ordered online and smailed...who would know? Just thinking outloud, as this is one of the very rare medications I will use without worrying. When this issue happened to me, the biologist said it would not hurt to medicate the food of all new fish acquisitions in the QT for a week, if I wanted peace of mind since internal protozoan have no external signs until it is too late, and they do seem to be more prevalent at least in NA.

 

[Essjay]

Amazon don't sell it and there is one seller on Ebay who claims to have one pack - at £45 plus postage, the same as 45 small cardinal tetras or 30 large ones at one of my local shops. A vet's prescription would probably cost less than that.

Strictly speaking it is illegal to import antibiotics without a prescription/licence. The question is - will a single pack be stopped at customs or are they only looking for bulk imports?

 

[lukesfishies]

Righto so I have some updates. Since yesterday night, we've lost two more. One during the night (the one that was being dodgy) and another one today. I've picked up some API melafix and stresscoat+, along with a roughly 60% waterchange, gravel vacuum, and some fresh gravel. I did find a symptom on the last one, it had a big colourless spot on its left side (I've added a pic). I euthanized this one as it went dodgy, then it was just fully vertical and breathing heavily for about an hour or two, so it was clear it was going to die. He's still alive in the Pyrex bowl, it's only the one on the tiles where he's dead

 

[lukesfishies]

Antibiotics are hard to get sadly, hopefully the stresscoat and melafix will help. There's also scaleless fish in the tank (Pakistani loaches) so we can't do salt.
Now it seems one of the guppies has gone a bit weird. It's active, but it's always at the top of the tank and it's fin is not in the best shape

UPDATE: We just got home, and now one of the previously very strong and big guppies is swimming upside down, and is now lying on the ground. He's jn great shape and he's grown terrifically since we got him. One of his side fins is stiff

 

[lukesfishies]

The guppy can't swim properly because the one fin has gone stiff so he keeps getting himself trapped in plants

 

[lukesfishies]

This is the guppy now. He was very strong and active before today, since we had him

 

[lukesfishies]

I'm talking about two different guppies. The one in the photo is not the one that's always at the top. The one in the photo was one of the healthiest fish in the tank until now. I put him in the jar to separate him. He's either floating upside down or on his side, looking dead, or trying to jump out of the jar. When he was in the tank he would purposely trap himself in plants of between the filter and the tank glass

 

[Retired Viking]

Sorry that things are going from bad to worse, Guppies are hardier than many fish, can you separate them from the tank and give them the salt treatment as @seangee suggested in another container. You can run and air line and stone to a bucket or something for them to stay in.

 

[lukesfishies]

Sorry that things are going from bad to worse, Guppies are hardier than many fish, can you separate them from the tank and give them the salt treatment as @seangee suggested in another container. You can run and air line and stone to a bucket or something for them to stay in.

The problem is the other heater doesn't work. Do they need another filter too? I have another 30l tank, if I were to get another heater, will it need a filter/cycling/ etc? The tank is empty and hasn't been used in months

 

[lukesfishies]

The guppy died.
Apart from the stiff left fin, he has a weird dark area at the top, behind the head. He was extremely healthy until we got back home just now, we've only been away for about 4 hrs

 

[lukesfishies]

We took new water measurements, and ammonia and nitrite are 0, and nitrate is less than 5ppm

 

[Retired Viking]

Guppies can handle water at a wide range of temperature so a heater will not be needed for now as long as your keep your house above 60 degrees, Place them in the bucket of similar temperature water as the tank, the water temp will drop to around the temp in your house after awhile but as long as it is a slow drop and not rapid they will be alright.

 

[Retired Viking]

You will have to do water changes to keep the ammonia level down and test for it since the tank is not cycled. Keep the amount you feed them small, that will also help with ammonia. It will be like a fish in cycle. As @seangee stated you will have to maintain the salt levels when doing the water changes too.

 

[lukesfishies]

OK so I gave the guppies and the tetras a salt dip, following instructions from here https://www.thesprucepets.com/using... external parasites, a,for five to 30 minutes.
4 teaspoons of salt in a gallon of water for about 15 minutes.
The tetras seem quite pale

 

[Retired Viking]

Tetras both neon and cardinal become pale when under stress