Help please fish dying!

[Jackjack]

we brought a 60l tank in nov and did a fishless cycle for 4 wks when prt shop said all ok and stated with 3 zebra danios, then slowly built our stock up with 6 tetras and 6 guppies. All was well did 10o/o water changes fortnightly, cleaned filter monthly, got a gravel cleaner! Then over a10 day period we lost 6 fish. No idea why. Have added extra bacteria stuff to improve water quality and will get a testing kit so we don't have to keep going to pet shop.that was three weeks ago have just now lost a danio. Now have 1 danio, 1 guppie and 5 tetras. What am I doing wrong?

have you checked the temp of the water and the PH LEVELS, Nitrate and nitrite levels and ammonia levels?
Have you got an air stone plus pump adding extra oxygen too?

Are there any symptoms? How did the fish look when they died?

I don't have testing equipment so took sample to pet shop who said nitrates were top end of ok. The fish appeared ok dying over night. We don't have an air stone, should we consider one? Pet shop suggested we place filter so it ripples surface which we've done. Have a thermometer which ds checks daily and is ok.

Yeah, I would get an air pump and air stone, as it helps oxygenate the water better.

It sounds like it's poisoning of some sort tho. have you been treating the water you have been topping up with fresh start each time? etc...

10% water change a fortnight is not enough in a tank your size with the fish you have. I would be doing around 30% a week, if not more. You should probably clean the filter with every water change too, your tank is quite heavily stocked. Are you using water from the tank to clean the filter?

I would also get your own test kit as being told that your nitrAte is 'the top end of OK' isn't very helpful!

Airstones are not essential but they can help a bit- moving the filter so it disturbs the surface of the water will probably do more to help gas exchange.

Can you get a test kit and/or get the shop to test again and write down what the levels are? You won't do any harm by doing a big water change.

What sort of tetras are they, neons? (those are the little blue and red ones)

Yes we have neon tetras. I did use the old water to wash out the filter. I'll try to get water tested again as soon as. Thanks all

Have tested water today -
Chlorine 1.5
Ph 6.8
Carbonate 6
Gh 8
Nitrite 0
Nitrates 25

I'm asuming all is ok except chlorine so I've added some chemical to counteract that.

Thanx x

Well, zero nitrIte is good news, nitrAte is low enough... bit worrying about the chlorine though. Which dechlorinator have you been using? Does your water board use chloramine?

Been using aquacare water conditioner, is that any good? Not sure about chloramine. Thanks for your replies x

The only aquacare I know of is a plant fertiliser- who makes it? Have you been using it at every water change? Chlorine isn't just a concern for the fish, it can also kill off all the good bacteria in the filter and cause the ammonia level to rise. Have you got an ammonia test kit?

Not sure if it was the neons you lost but they're not very hardy fish in a newly set up tank. I found this out by losing most of my first shoal. I left it about 6 months til I bought any more neons and theyve been ok since.