Sorry for the length of the post and the lack of a picture.

Basically my question if you are in a hurry is are Pearl Danios peaceful community fish when mixed with White Cloud Mountain Minnows ?

Otherwise the full story reads as follows :-

My kids wanted Goldfish.

We went to the shops to look at options.

We looked at 20 Litre tank in one shop and went on, when they did not have one in stock ( two goldfish....).

At second shop 35 litres was absolute minimum they would recommend for goldfish and they suggested a shoal of smaller fish may be a better option. They tried to sell us a larger 60 Litre tank.

So we bought the 35 litre tank, set it up. Two plants. Internal oversized filter as was 'Goldfish kit'.

Looked on the net and persuaded kids to have smaller fish but they wanted to know whose fish were whose so we suggested two small schools and the kids agreed.

Then went back after a week as suggested with a water sample. The water was OK for fish... so we took home 3 Pearl Danio and 3 White Cloud Mountain Minnows and a "Borneo Sucker".

So far so good.

After a couple of days a minnow died, new tank syndrome.

A few days later due to my reading about minimum shoal size and stress we introduced a couple more minnows. ( Not enough reading about tank cycling though or we would have put in less fish to start with or perhaps even tried fishless cycling ).

A day later one of the new minnows died. Followed by the other new one a week later. Some doubts starting.

I was changing 10 % of the water weekly. Using Nutrafin Aqua Plus dechlorinator and adding 5 ml Nutrafin cycle to tank after adding the new water which was left overnight after adding dechlorinator.

We are now 3 weeks in. A quick visit to the shop with a water sample - nitrite high. 5 ml Amquel+ added and again 24 hours later. This is supposed to allow cycling to continue rather than having to start again.

3 weeks later and about 6 weeks after introducing fish we added three more minnows after the shop tested the water and said it had now cycled. Now 3 Danios and 5 Minnows.
( Plus the Borneo Sucker ).

2 days later one of these new minnows died.
Followed by the other two new ones over the next 9 days.

So the 3 Danios are still there, plus two of the original minnows. Getting quite concerned.

The Danios are quite active, the plants were starting to get rather overgrown and the latest two casualties were found IN the weed which the Danios were going through at speed. I did not see any obvious 'bullying' though there was an occaisional chase of minnows by Danio.

Not sure if the Danios are the cause, rather puzzled by the fact that the two original minnows are still with us ( more golden than the later ones ) while the latest additions died. The first minnows would have been subject to any 'bullying' for a much longer term.

Any ideas on things to check or keep an eye out for ?

Hi Ogri. Welcome to FK. Sorry it's in such circumstances as those.

The short answer is yes, Danios and WCMMs are compatible. However, danios are fast-swimming shoaling fish which really benefit from a 3ft long tank. Being shoalers, both WCMMs and Danios should ideally be in groups of 6+, but the more, the better.

Do you have any test results at all for ammonia, nitrite, nitrate and pH? If so, could you post them in ppm or mg/l, along with which test kit you're using? GH and KH would help too, if you know them. These will help rule out any problems with water quality. If you don't, might I suggest you buy your own test kit, rather than rely on the pet shop? They do tend to say "it's fine" or "it's a little high", which to us is "a little vague". Ebay sells the API liquid master test kit for half the price on the high street.

Anything out of the ordinary about the fish just before they died? Any spots, fluff, fin damage, red streaks/patches or behaviour changes?

Sounds to me like the fish have been succumbing to water quality problems - high levels of ammonia and/or nitrite. When cycling with fish, water changes need to be carried out daily, rather than weekly, because you need to remove the toxic ammonia and nitrite from the water until the filter can catch up.

Hi Orgi, Welcome to the site.

May I start by saying sorry because all the news I am going to give you is bad news. Please read the BVA article in my Signature

Firstly all of the advice your fish shop has given you has been wrong. Did they write down the results of the water tests for you? Also did you see them doing the test?

1) A minimum tank size is 45litres and this will house 1 single male Betta. If you did go for Goldfish you would require a tank of 140litre minimum. The tank you have is already overstocked.

Goldfish size and life expectancy.

A beginners guide to buying the correct tank

2) The Tank should NEVER be cycled with fish in it. The fishless cycle is the only way to do it these days as governed by the Animal Welfare Act. Tanks take a minimum of 6 weeks to cycle properly before adding any fish. The water you had taken to your local shop was obviously not ready for fish. In order to carry out this task properly you require a water test kit. These are in liquid form, do not bother with the test strips as they are so inaccurate they are deemed useless. The test kit is not an accessory it is one of the most important items you could buy. The Nutrafin Cycle is not worth adding as it doesn't actually do anything. By continuously adding fish you were just overloading the Bio-load of the tank so much so that what little bacteria the tank had built up was being overwhelmed and the ammonia levels in the water were rising to very high levels, this is why your fish are dying.

Fishless cycling

API MAster test KIt on Ebay


I would take your tank and filter etc back to the shop (Which shop was it, not one of those big pet stores?) where you bought it all and ask for your money back, including the money for the fish that have died, as all of the equipment was not fit for purpose. Print out a copy of the BVA Leaflet and take that with you as back-up. Then go to a shop that specialises in fish. But first check to see what your tap water parameters are first, i.e. Ph & water Hardness, as this will determine what fish you can keep.

Hope that all helps.

Sorry for all the bad news.

tank the tank back and get a 60 litre set up

then complete a fishless cycle

and then when ready and rocking get a schoal of WCMM they look great and easy to maintain

hope this helps

To all the replies ( thanks )

I understand what you are saying re the stocking levels.

Any ideas why if either bullying or water quality issues - and the shop did the tests within my view but I do not have any numbers - why the later additions succumbed first as they would have been subject to whatever was wrong for longer ?

It had been 6 weeks after the first fish, before the last 3 minnows were added.

There was nothing obviously wrong in terms of "spots, fluff, fin damage, red streaks/patches" other than they were the colour of banana ( not the peel, the inside ) but some of the fish both Danios and Minnows would go quite fast from top ( not breaching surface of water as far as I could tell ) to near bottom of the tank a number of times ( 5 or 6 ) in a few seconds, then calm down again. Maybe just hungry as we are keeping the feeding to just what they eat within 2 minutes ?

Thanks for your responses.

When the fish dart to the surface it is usually a sign of oxygen depletion, this would be caused by the build up of ammonia and other toxins building up in the water. The newer fish would go first as the original fish would have slightly acclimatised to the growing poor water quality. The newer ones would have been put straight into an ammonia soup and this would have caused their speedy demise. Ammonia poisoning doesn't always have obvious signs, bright red gills is one sign that is caused by ammonia burning the membranes. A short term remedy is to replace %0% water today, and then 10% everyday for the foreseeable future. In the long term you will need to get a bigger tank of 100 litres minimum for the stock you have and then cycle that tank before adding anything. If you can, rehouse your present fish either with a good aquatic shop, or somebody such as a friend who has fish, then get a new tank, cycle the tank/filter for minimum 6 weeks and then put your fish back in. I am very sorry to say that if you do not get a bigger tank you will loose all of your fish and end up with an empty tank. Do not buy any more fish for your present set-up.

You will need to buy the water test kit linked to earlier in the thread as this is the only way you can be totally sure of water quality by testing your own water. Never trust the shops as they are there to sell, sell sell, and they will do so any way they can. They are there to make a profit. If you look around there are a few shops that do think of fish welfare, but they are very few and far between unfortunately. Never completely trust the advice given by shops, do your own research, and make your own informed decisions. This site is a good start.