Fish are dying - Water parameters seem fine

My father gave me his fish tank along with the fish that he'd had in it.
The fish were 2 white skirts, 2 black phantom tetras, 1 orange danio, 1 pakistani loach, 5 neon tetras (All fish were 1-3 years old).

I rehomed the orange danio and pakistani loach after a few weeks (During that time, there was no evidence of them being sick/dying/unhappy). I also moved the 5 neons across to another tank - all of them are still alive and happy.

After all of the fish rehoming, I bought 5 guppies and 2 black phantom tetras to add them to the tank.
Over the course of a week or two, 3 of those guppies died. But I noticed that the white skirts were munching on their fins. I even watched a guppy die immediately after its fin was nipped I was very sad about the 3 guppy deaths, but at least I thought I knew what was killing them.

I then rehomed the white skirts, and bought 5 new guppies. So at this point, the tank was 7 guppies and 4 black phantom tetras (With 3 guppy casualties). Over the next week, one of the new Black Phantom tetras died, as well as another guppy. So I guess the white skirts weren't the only issue with the tank.
At this point, I had no idea what's killing them.

During all of this time, I had been using my Sera ph, nitrate and nitrite tests. From my readings, ph was 6.5, nitrites was 0, and nitrates were about 5-10ppm.

To check my own sanity, as well as Cl and ammonia, I got my water tested at the LFS (Who - to my disappointment - just used a strip test. Not sure if that's normal). But from their measurements, there was no Ammonia or Cl. But using their pH testing wand thing (Not sure what that tool is actually called), they said my pH was 6.1 (Not sure why their result was so different to my Sera test). Even if my 6.5 reading was correct, I supposed it was a bit on the low side, and my fish were clearly unhappy. So I added some pH-up stuff, and it went up to 7 according to my Sera test. I hoped that this would be the end of the fish deaths, but this morning I woke up to 2 more fish deaths. Upping the death count to 6 guppies and 1 black phantom tetras. This is all becoming too much for me now. What on earth could be killing all of my guppies.

Edit: Video of the remaining fish
https://imgur.com/gallery/9MMihag

 

I have not noticed anything like that, but since I'm new to the hobby, I may not know exactly what to look out for. I noticed that after the fish have died, their eyes and bodies turn white, but I presume that's normal

I have uploaded a video of the fish, they move around a lot so it's hard to get photos or even a very steady video, but hopefully its good enough.
https://imgur.com/gallery/9MMihag

I dont think the pH stuff I'm using increases the hardness. Its just some cheap Daro stuff that the LFS recommended - according to the ingredients, its just baking soda.
Unfortunately I don't have anything to test the KH. Wonder if I should buy a KH test or just skip that and buy something to increase the hardness

Edit: Just realised I forgot to reply to the initial part of your message. Its a 45L tank and I do about 25% per week

 

neither your pH nor your KH will kill fish in the manner described.

I watched your video and they seem fine.

So I wonder if it's something else- check all your electrical things in the aquarium - heater and filter, lights if the cables come anywhere near the water.

Could anything else have gotten in to the water? Either a poisonous substance, or perhaps an insect larvae, like a dragonfly larvae?

What dechlorinator do you use?

Please do google columnaris, and fin rot, as possible things going on - I don't see any signs in the video (maybe some unhappy fins).

47 l is small but should be ok for a bunch of guppies and some black phantom tetras.

 

I really suspected chlorine in the water. I was using some cheapo Daro dechlorinator (Replaced it with an aquadene one now). But if the fish shops strip test is to be trusted, there was no chlorine in the water. I also hadn't done a water change for about a week and 2 fishes died last night. I figured that after a week of my airstone running, even if there was initially chlorine in the water, it probably wouldn't still be in there. So I mostly ruled out the possibility of it being chlorine.

The only way I can imagine something dangerous getting in the water is through the fish shops water from when I bought the first batch of guppies like 2/3 weeks ago - since I just dumped all of their water in. The second time around I fished them out individually to avoid contaminating my tank with their water. Maybe I was stupid the first time around, I hadn't really thought of the danger of adding their water to my tank.

Perhaps I should dose my fish with Kanaplex. It's the only medication I've currently got, but I'm worried about using it with the red cherry shrimp in my tank. Seachem reckons its not safe. Maybe I can just add it to the fishes food to mitigate that risk a bit.

As for the electrical stuff, I presume you mean checking if they're shocking the water or something? Its an interesting thought, but my hand has been in the tank a few times and I haven't been shocked. Unless the voltage is too low for me to feel or something like that.

One very peculiar thing that I forgot to mention in my original post is the manner in which the fish die. I watched 2 fish die, and it was very strange to me. Perhaps its normal, but maybe it could be used as a clue for what could be causing the deaths...
For a lack of a better way of explaining it, they seem to die and revive themselves multiple times before their final death. As in, they literally flop over and sink to the bottom of the tank as if they're dead.. for like 5+ seconds, sometimes even like 30.. and then they pop up again and swim around for a few moments, before they die again, repeat this a few times until they eventually die for good
I wondered if it was lack of oxygen or something, and their revival was due to them getting a bit of oxygen back or something. So I added another airstone since then, but the fish are still dying.

 

You mention running airstones - I assume you have a filter running too?

 

Yes, of course! It's a pump which pulls water up above the tank and then it pours down into a tray with foam and carbon and ceramic things before pouring back into the tank. Curious to know what this type of filter is actually called

 

Either an overhead filter box or hang on back. Former being my best guess.

 

With regards to the fish dying. Maybe you have chloramine and not chlorine. I personally wouldn't use any other dechlorinator than seachem products. I've used aquadene recently when it was the only thing available while I waited for my seachem safe to arrive and I honestly felt like it didn't work. Also the dosing amount made me feel like it was heavily concentrated. Think it was 5ml for every 10gallon while prime if I'm not mistaken is 1ml. I'd try to get my hands on prime and take it from there. Also with the strips some of them you need to check at the exact moment (example chlorine at 45seconds, nitrates at 60seconds and) and this becomes quite a nuisance if you're not sure exactly how long to check in as sometimes checking too soon or late gives you incorrect reading

 

I just asked about the filter because it could be that there is ammonia in the water. Not many test strips actually include ammonia. Do you by any chance know which brand they used? If it's jbl it doesn't have ammonia, just nitrate and nitrite (and other things) (I use that one because it's what I could get and is better than nothing, but just mentioning it in case the lfs just told you it's zero but they didn't actually check it).
I would think though that if your nitrites are zero and you do have nitrates then it probably isn't ammonia. It just does sound like poisoning of some kind (which is why I thought ammonia).
I'm pretty new at this myself though so hopefully others that are more knowledgeable might be able to make other suggestions based on the way the fish die over and over before actually dying

 

Some of the more affordable dechlorinators around aren't completely effective, as @Shabir mentions, they don't remove chloramine.

You'll need to provide more info, there's too many variables in an aquarium. If the flopping happens after a water change, it might be chlorine, chloramine or even ammonia or a pH spike depending on how much of water change it is. But ph issues usually happen when introducing new fish coming from vastly different ph water, the fish bob and dart around at the surface.

Maybe look more closely at the fish and see if you notice anything. Have a look here for descriptions of common diseases.
https://www.jbl.de/en/essentials-aquarium-diseases/section/96/diseases?country=us

One thing I noticed in the video was the gold guppies gill area looked red. Live bearers are notorious for being parasite carriers.

 

By the way, baking soda (Bicarb) does increase the hardness. But it's a short-lived solution. I use it in my goldfish tank because I do big frequent water changes so other things like crushed coral are ineffective as they are much slower acting.
So the pH up will increase both your pH and your water hardness, but it will do it quickly and only short term.
The crushed coral (or aragonite) etc is a more stable way of keeping your pH and water hardness raised. They work much more slowly but also keep it more stable long term.
The latest deaths *could* be from increasing the pH too quickly.
Though given they happened so soon after the other deaths its unlikely.

When you introduce the new fish to your tank, do you acclimate them at all or just add them straight out the bag into your tank?
(by acclimate mean gradually add your water to theirs to get them used to your water parameters)
It's possible the answer is as simple as shock due to sudden changes in water parameters.

 

Sorry to hear. How old is the carbon? Most people don’t use it these days except to remove meds.

 

Yes, its an overhead filter box. Thanks for that

Damn, okay. Pity that it seems like the Aquadene one might not be good enough. Only just bought the stuff. Oh well, at least it was cheap.
I wasn't aware of the time limit on checking the different measurements on the test strips. Its possible that the guy didn't do that correctly. He didn't really seem like he knew what he was doing.

Unfortunately I'm not 100% sure of the test strip they used. It does look a lot like the JBL one though, if my memory serves correctly.
I was also running on the assumption that nitrates being 0 and nitrates being above 0 means that I probably don't have ammonia. I've been considering just buying a test anyway, even though I thought it would be quite likely to show that there's no ammonia, but for some reason none of the pet shops I go to have ammonia tests.

I will be replacing this Aquadene stuff with some Seachem Prime in case the cheap dechlorinator is the issue.
The strange thing though is that the fish deaths don't seem to be linked to water changes. I hadn't changed the water in about a week, and 2 fish died last night. I'd have thought that chlorine/chloramine would kill them quicker. A search on google said they'd die within 24 hours. But perhaps there's low levels that killed them slowly - If that's a possiblity.

Regarding the redness around the gill area - I'd just assumed the redness was because its a light coloured fish, so it was normal.
I've taken some more pics if you don't mind having another look. The redness is noticably more visible when viewing from below. Still not sure if its a cause for concern, or just because he's white-ish.
Yellow fish short clips - GIFs - Imgur
I know its still not very clear, but let me know if it alarms you.

Another thing that concerns me is that the guppies seem to spend a quite a lot of time near the surface of the water.
They aren't permanently at the surface. They spend a good amount of time foraging in the plants too. But this eve they're very clearly spending most of their time skimming along the surface. If I was being optimistic, I'd say maybe they're just hoping to find some food. But I've noticed this at various points throughout the day. Searching google didn't bring me much closer to an answer though. It seems like that could be a sign of many different water parameters or sicknesses. Its definitely only the guppies which do this though. The black phantoms are pretty much never at the surface.

Thanks for this. I will look into the crushed coral or aragonite if pH continues to be an issue.
I also wondered if the recent deaths were just shock from the pH changing.. but like you say, considering all of the other deaths, it could be unlikely.
Also, I changed the pH on Friday, and the first deaths since then were Sunday night. I think I'd expect the reaction to be faster, if they were to get shocked from the pH change.

As for acclimatizing them. With the first batch of guppies, I didn't acclimatize them. I thought that might have been an issue, so with the second batch I did. Not sure if I did it correctly though. I added like 50-100ml or something every 5-10 mins. Probably had about a 50:50 ratio of the two waters before just adding the fish in. I wish I had an accurate timeline of the fish deaths. But I'm pretty sure the first death in the second batch of guppies was more than a day after adding them. I think it might have even been multiple days. Which kinda made me think it wasn't just shock, and more likely something with a slower effect

 

Oh really? I thought carbon was important to have in the tank to remove bad chemicals and stuff. The carbon is a few months old. Maybe 3/4ish. Should I just get rid of it? Not sure what I'll do with all of the other space in the overhead filter box

 

Lol add more bio Media in that space. Or a sponge cut to size will also filter and hold a decent colony of bacteria.

 

Not all test strips have that timeline but some do. So it depends on what brand they were using. I also use a top filter together with a canister and I find the top one is excellent for oxygenation but could leave dead spots in your tank. Not entirely sure how yours is set up though. If your fish are gasping at the top it's a sign that something's draining them ox oxygen but if they're just hanging around swimming at the top normally I wouldn't be too concerned. Are the deaths limited to just the new fish added or has some of the fish that were already in there been affected too?

 

Hi @Craigils .

I suspect you found the issue, they started adding chloramine here in the Cape recently. I used a carbon block for years to take the chlorine out with no problems, when that salinity plant came online I had to start using prime and safe again. They gave no warning before hand and I lost a lot of fish. Chlorine test showed no chlorine also. The news said the people helping the government where from Australia and that the funny taste and smell is not harmful to humans, all this a week later after people started complaining about the taste and smell, talk about captain hindsight. They didn't name the chemical but I went on the Ausie government sights to see what they use over there for water treatment and yes it's chloramine.

Where your fish hard and a little swollen when you took them out?