got my daughter a small 25L tank for her b-day in september, put 3 goldfish in it. was fine for about 3 weeks, did the same for it as my big tropical tank, gravel vac- weekly water change. goldfish started dying off 1 by 1 & i kept buying more & the same thing, they would last a couple of weeks & then die aswell. took most of the water out & replaced with water from my tropical & small amount of fresh water ( told by lady at lsf to do this ) things where fine for a couple of weeks then started again. i gave up with goldfish, completely scrubbed the tank put water from my other tank in & put 5 guppies & 1 borneo sucker in ( with a heater of course). now 1 dead sucker ( think i may have crushed him but not sure), 1 dead guppy & another one about to die, what the hell is wrong?? could it be the tank, can the wrong silicon (sp) been used? dodgy rocks? all had been well cleaned. there was one goldfish left & i put it out in the pond with the others & yip that died too. so i have no idea what to do or whats going wrong

Do you closely monitor how much your dauther is feeding?

Also it could be that you are keeping the tank too clean and killing the bacteria that drive the nitrogen cycle.

Are you waiting for the tank to cycle before adding fish? just moving water from a running tank doesn't avoid the cycle, there is very little bacteria in the water (compared to what its on the surfaces of filter media, gravel etc). The only way to MAYBE skip the cycling is to move a mature filter off a running tank onto a new one.

Suggest you get you water tested and post the results, plus any info on filters etc.

I dont know how old your daugher is but also keep a close eye on how much she feeds and what else she does in the tank (i.e. maybe it's also barbies swimming pool :lol: )

lol, yeah i watch the feeding & she is doing well not to over feed them, might have to take the fish out & leave it for awhile to cycle with the snail??

25L is also very small so when something goes wrong, it does so quickly and easily. It is way too small to put 1, let alone 3 goldfish in. Being fine for 3 weeks makes me think they died from ammonia poisoning etc. Waht sort of filtration does it have on it?

no filter & i gravel vac once a week, just has 6 guppies & 1 snail & a few bn fry. went back to the lsf & they said to change the water again with the water out of my big tank & a small sponge filter could help. the goldfish that were in it were tiny & were told they should be fine in the tank

goldfish are up there with some of the messiest fish (large cichlids etc), they arent too great at digesting their food (or so im told) which means they produce more waste and need more room than your average small tropical fish.

your gravel isnt that coloured stuff is it? ive read that the paint can come off sometimes.

i would get the water tested (ammonia, nitrite, nitrate and ph) and perhaps look for a tincy wincy internal, i have a tiny internal which is about 10x4cm that does 200lph, im sure there are ones smaller out there. i have seen tiny HOB's over in the states which are used on betta tanks (mini filters are cute lol) but im not sure if theyre available here. a filter isnt just gonna airate the tank it will give the bacteria a good place to grow and help keep things more stable.

it doesnt sound over stocked or over fed but i wonder if it is spiking for some reason?

Your problem is NO filter with Goldfish.

As Sharn said. Goldfish are filthy buggers.

You definitely need a filter for them.. or you change the water daily.

i'll take some water in to be tested before i change it & some more in later in the week for an idea of whats going on, theres a missing guppy this morning, cant even find bones, im guessing the bn bubbs

it could be cursed i had a tank that what ever i put in ther died then tryed beeding my discus whouch would breed find just wouldent eavent go near each other until i moved them then they were fine so i put it down to the tank so now its gone and all good its good to know someone els had the same things as me

haunted fish tanks!

I have never been able to keep goldfish, never.

Corals and marine fish, no worries.

Strange

I thought my large tank was cursed when I got it... took a while but I figured it was the gravel that we bought from the LFS, white stuff.

After a few days the tank smelled sour, the fish were struggling etc. After a crash water change everything came right for a while then same again.

Removing ALL gravel & just going bare sorted it. It actually felt like the gravel had been stored near pesticides or something it was so toxic.