Fish Dying, New Tank Help.please 😔

Hi all hope this is the right place to post, couldn't locate anywhere else..
I have a 37l aquaone tank with the back filter hang on system, heater interpret 200watt(the shop gave me this as the recommendation) temperature was on 79.

Purchased a Betta, two penguin tetras, 2 rummy nose tetras and two neon tetras(as advised in shop now realised could have done with more neons etc)

All seemed fine entered tank, ate food swam around, overnight things changed. First rummy nose went missing. Both penguins began gasping at the bottom fins looked torn, never saw the Betta make an attack on them at all, but did see him go for the tail of the remaining rummy nose once no damage although gasping like penguin. An hour later he was dead. Turned lights off penguins swimming at the top quickly thought they were getting better as gone from bottom still to swimming but by the morning both dead. Have found the missing rummy nose too. Both neon tetras went missing but appeared back and are ok?! Except I have noticed a single white spot on the fin of the neon tetras his mate kept going for him. Could it be ick being one spot?

Went back to shop they tested water said it was fine, I explained about the swimming at the top said could be oxygen but I said I have the filter with water entering from above to create bubbles, said could have been the fish given so exchanged for 2 cherry barb, 2 zebra danio, 2 dwarf rainbow and 2 minnow.

Rested on top, added tank water, were eager to get out, swam like normal, ate food the danios ate majority which concerned me. Male rainbow barb started attacking female and other fish, one danio going for his mate Later all but the rosy barb and neon were circling the top of the tank, did a small water change and added attachement to try create waterfall of water entering even though before there were lots of bubbles. Turned heater down gradually to 75. Seemed a bit better. Still alive today except lost the female dwarf rainbow, had a glimpse of male earlier but nowhere to be seen now so concerned for him. Danios and minnows still frequenting around the top more so the danios, changed a quarter of water again but still there, tried small but of food danios ate a bit but not much, rosy barbs hiding around the bottom but come up to the top.
Is there anything anyone can suggest I need to or can do asap? Thanks

I'll start right at the beginning.

Fish excrete ammonia, it's their version of urine. But it is toxic to fish - it burns their skin and gills making it difficult for them to breathe. In an established tank, there is a colony of bacteria which eats ammonia and they turn it into nitrite. Unfortunately, nitrite is also poisonous - it binds to the blood stopping it taking up oxygen. But in an established tank, a second colony of bacteria eats this nitrite and turns it into nitrate, which is less poisonous than the other two.
There are none of these bacteria in a brand new tank, they have to grow and this takes several weeks. The process of growing these bacteria is called cycling (the name comes from the nitrogen cycle, ammonia -> nitrite -> nitrate)

You are doing what we call a fish-in cycle. The danger with this is that the fish can be harmed. Gasping at the surface is one symptom - becasue they can't get as much oxygen into their bodies they try to gulp it from the air.

OK so that's the background to what is happening in your tank. Now for the way forwards.


The first thing is to do a big water change. Remove as much water as you can, leaving just enough so the fish can swim upright. As long as the new water is the same temperature as the tank water and you remember to add water conditioner, this will not harm the fish. Do this every day until you have your own testers.
Do not believe anything a shop tells you. Most of them haven't a clue. That includes telling you that the water is fine when it is not fine.

Buy a testing kit as soon as you can. Liquid reagent ones are better than strips. You can buy master test kits but if you don't want to spend that much money all at once, get just ammonia and nitrite testers as these are the killers.
Then test the tank water every day for ammonia and nitrite. Whenever there is a reading above zero, you need to do a water change, a big enough water change to get the level down to zero.
At first there will be only ammonia in the water, and it will go back up again after a water change. Soon, nitrite will show up. The speed with which ammonia goes up will slow down, but nitrite will then start to shoot up fast. After a few weeks, ammonia will drop to zero and stay there - that's because enough bacteria have grown to eat all the ammonia made by the fish. But nitrite will still go up, then it will slow down, then drop to zero and stay there. When you've had a week of testing when both ammonia and nitrite stay at zero, that's when the tank is cycled.

There are things you can do to speed it up.
Tetra Safe Start is one of the most highly recommended bottled bacteria products. Adding that will help, though it's not an instant fix.
Seachem Prime detoxifies both ammonia and nitrite for about 24 hours. After that time they become toxic again, but it keeps the fish safe between daily water changes. Although they are detoxified, ammonia and nitrite still show up in the tests.
Get some live plants. Even just a couple of bunches of elodea left to float will help. Plants take up ammonia as fertiliser and they turn it into protein rather than nitrite.







But I have to tell you that you were very badly advised about the type of fish.
All the tetras you bought at first need to be in groups of at least 6 in much bigger tanks. In the wild they live in groups of hundreds if not thousands of their own kind and if there are only a few of them they get very stressed.
Then they sold you cherry barbs, zebra danios, rainbowfish and minnows. Again these are shoaling fish which need a group of at least 6 and a much bigger tank.

 
A 37 litre tank is perfect for a betta - just the betta and no other fish.
The best thing you can do is take all the fish excpet the betta back to the shop.


I know you don't want to hear all this but the advice from that shop is just terrible 

Thanks so much this has explained things to me perfectly and yes it is quite shocking to me how wrong the information I got from the shop is!
They said water was 'perfect' too...!

I went to two as well, the first even put the Betta in the same bag as the others to travel, then when they passed and I went back to the other store they gave me all those in one go! I have since rang to ask if I can return the danio due to becoming aggressive as he was left by himself as the other passed this time the woman said 'were you given all those fish in one go?' and reference d overstocking / waiting until stable before adding more (after finding out cherry barbs are also shoaling fish and the other passed I didn't want him to be on his own so asked if I could swap the danio for another barb). However now with you mentioning 37l only ok for the Betta, it's a bit rubbish they have said I could actually have 15 small fish with the Betta if I wanted!

I asked if any could be by themselves and the only thing was 'best to just get two together' nothing mentioned about should be part of a school minimum of 6 etc, why do they do that 😢. They did seem very knowledgeable about which fish get on with Betta etc so I just thought they knew what they were talking about.
 
Although I do like this tank it's modern looking I'm now rethinking my choice! Is there a particular size would you recommend to be able to keep Betta and shoaling fish such as neon tetra?

Thanks I've got three plants in there java fern on a piece of wood and two others I've lost the name to one has purple under leaves the other is a taller type.

Also something I've thought after adding substrate mines a thick layer and the filter pack on the pack cave ornaments etc this means it's no longer 37litre?

Now everything has gone day by day 😔 despite water change but maybe I didn't do a large enough amount and the cherry barb took to hiding in a small cave, I'm wondering why they became ill but the others (currently) seem ok? I still have the Betta(thankfully) the two neon tetras which seem ok and the two minnows although I still haven't seen on eat after being harassed by the danio.

I have the filter in the back which blows out the water through a tube and has an attachment piece of plastic so water is able to be propelled higher in to the air to create more of a flow as I was worried there wasn't enough oxygen but the Betta doesn't seem to like the flow so much and it seems to be reaching far down to the tank possibly disturbing any food/fish waste so not sure what to do there?

Ive taken a break from feeding after adding food and not so much being eaten this time I don't want to leave it too long but conscious of too much waste in there.

Thanks I have bought the seachem prime(although difficult to know how to add as a capful is for 200l!) And the tetra safe start but wondering after adding the tetra safe start and doing water changes am I u doing that by adding the seachem every day?

I've also ordered the master api test now too it should be here by Sunday hopefully. I need to also find a good vacuum for the gravel though too

Bettas are solitary fish which are best kept on their own, maybe a snail for company. As Littlefish said, if you want shoaling fish a second tank is a better option and keep the betta in the 37 litres.


Smaller tetras such as neons need a tank at least 60 cm long. Tanks vary in height, I've had a 54 litre tank which was 60 cm long and there are 70 litre tanks with the same floor area, just taller. If you could manage a tank which has a 60 x 30 cm footprint (floor space) there are several species to choose from.

Littlefish asked about your tap water hardness. Some fish come from places with soft water, others come from places with hard water. If soft water fish are kept in hard water or hard water fish in soft water it will affect them. Their bodies will not be able to cope, they will get sick more easily and they won't live as long as they should. We should try to keep fish which come from roughtly the same hardness as our tap water.
Can you tell us the number the water company gives and the unit of measurement as there are several they could use. Many use words to describe hardness to they can be misleading (mine says slightly hard but looking at the number it's actually soft!)
If you can't find your hardness, tell us the name of your water company and we'll see if we can find the page on their website. There's usually a section where you type in your postcode and that gives your hardness and water quality report.

Re what the shop said, so that you know the truth -


Wild bettas survive (or some of them do) in puddles of water during the dry season. Their normal habitat is a vast area of shallow slow moving water - think rice paddy. That's wild bettas with short fins, not the commercially bred bettas with their huge fins. The reply to anyone who says they live in puddles is - in that case, how do the males meet the females to breed?
The minimum size most of us accept for a betta's tank is 20 litres (or 5 US gallons) and bigger is better. Though it does reach a point where we think - should I really have a tank that huge for just one fish?


Water changes are what keep the fish alive. Ignore anyone who tells you not to do them during cycling. The bacteria we need to grow live in the biofilm which is bound tightly to surfaces, the bacteria do not live floating in the water. The only way water changes will harm the growing bacteria colonies is if you forget to add water conditioner to remove the chlorine in tap water - and this will also harm the fish.
There are many people who believe that ammonia and nitrite levels need to be high to grow the bacteria. But even a trace is more than the current numbers can eat so it will allow them to multiply. The important thing is to keep the fish safe.


Cleaning the filter - a filter shouldn't be cleaned for the first 6 weeks so that the biofilm can establish properly. After that it should be cleaned at least once a month, in old water taken out of the tank during a water chnage. The brown goo which builds up in the filter is fish poop, uneaten food etc which decomposes to make ammonia, which is turned into nitrite then nitrate. A filter which is not cleaned regularly builds up so much goo that it is one cause of of high tank nitrate.
The shop will probably also say that you need to change the media regularly. Filter sponges will last for years and only need changing when they go into holes or won't go back into shape after squeezing. Some filters have only carbon cartridges as media. If possible, it is better to replace those with any brand of filter sponge cut to the shape of a cartridge since carbon isn't actually needed and sponge is a better home for the bacteria. But if they can't be replaced, they just need washing on old water as well.
Chaning the filter media regularly will reset the cycle, water changes won't!






The ammonia test - with API ammonia, a lot of people never see the yellow of zero even with a tank that has been running for years with no problems. It is thought to be due to the fact that different eyes see colours slightly differently. Also, the lighting can affect the colour of the ammonia test. Flourescent lights, both tubes and energy saving compact fluorescent bulbs (if you still have any) can affect the colour in the tube. When possible, do the test in dayllight and read it in bright light but not direct sunlight.
Try to kep the ammonia level below 0.25.
[I can explain this further if you wish; because the amount of toxic ammonia varies with pH, it is possible to calculate how toxic it is at any particular pH so you can work out when you need to do a water change and when you don't. I know you are in the middle of a steep learning curve at the moment, so if you'd rather, just stay with keeping ammonia and later nitrite as low as possible]






Was it your water company (either in person or on the website) which said moderately hard?

When a water company says moderately hard they mean somewhere in the range 8.4 to 11.2 dH, and 150 to 200 ppm. Yes, fish keeping uses two different units for hardness, some fish profiles use one, some the other so we need to know our hardness in both.
There are many fish suitable for this hardness, you just need to avoid those soft water fish which must have very soft water and those hard water fish which must have very hard water.




Going forwards, always research fish before you buy them. If you use a smart phone, you can always step outside the shop while you look them up, then you don't have to listen to anything the shop says. Even better is to do the research first then go looking for the fish you've decided on.