Hey, I'm new here, wondering if anyone can help with this problem. I'm fairly new to fishkeeping, got my first tank in September. Over the past few weeks the water has been a bit cloudy. It's happened before but it usually clears up after a day or two, failing that a partial water change makes a difference. But this time it's been like it a couple of weeks and partial water changes haven't made any difference. Any ideas? I haven't tested the water quality but there doesn't seem to be any problem on that front, all the fish are fine, I've even got glass catfish in there which are happy and healthy. Judging by what I've read about them, they'll be the first to go down if there's anything wrong. Can anyone tell what could be causing it and what to do about it?

Hi and welcome to FK

Ok, we could do with a bit more info please to help if poss.

How big is the tank (litres or UK gallons)? If unsure, post measurements
What are your current readings for pH, ammonia, nitrite and nitrate? (this bit is very important - if you are keeping fish, readings are required as most toxins are clear, can you test now and post?)
Filter brand and size?
What is the current stock, give breeds and numbers?
How often do you undertake water changes and how much?
Do you use water conditioner, to get rid of chlorine and chloramines?

The more info the better the site can help….

Green water would be associated with too much sunlight/nitrates perhaps. A white bloom with bacteria.

Hi Violet, thanks for replying. In answer to your questions:

My tank is approximately 100 litres, 80cmx35cmx40cm.
My filter is an Aquael FAN-2 plus, output 450l/h, this was the filter supplied with the tank.
Fish - I currently have 56 fish, I know this may be a little overstocked perhaps but it seems to depend where you ask.
Breeds and numbers: 9 neon tetra, 3 glowlight tetra, 2 black neon tetra, 2 peruvian blue tetra, 1 octocinclus, 3 platys, 3 rummy nose tetra, 1 scissortail rasbora, 2 red honey gouramis, 3 cherry barbs, 3 black widow tetra, 2 swordtails, 4 zebra danios, 1 gold sucking loach, 2 peppered corydoras, 1 molly, 2 red tailed black sharks, 3 bengal loaches, 3 purple harlequin rasboras, 3 bleeding heart tetra, 4 glass catfish.
I do a 20% partial water change once a week.
Water conditioner - I use Tetra AquaSafe.
I'll buy the relevant test kits over the next couple of days and post the readings.
The water doesn't seem to be green, the water I take out when I do a partial water change is yellowish, presumably this is from fish waste? The cloudiness is more whitish I guess, so bacteria then.

Hi

Sorry to bear bad news, but your tank is more than a little overstocked; it is probably the most seriously overstocked tank I've ever come across, and that is the reason for the cloudiness - your filter cannot cope with the bioload of all the fish you have in there.

You have a 100 litre tank which is only likely to be 90 litres of actual water once gravel etc is taken into account.

I don't know how long your tank has been set up, but even in a mature tank the maximum recommended amount of stock is 5 cms per 4.5 litres. (90/4.5)x 5cms = no more than 100cms of fish (more than most would actually have regardless of the calculation).

Your current stock adds up to:

9 Neons @ 4cms = 36cms
3 Glowlights @ 4cms =12cms
2 Black Neons @ 4cms = 8cms
2 Peruvian Blue Tetra @ 4.5cms = 9cms
1 Otocinclus @ 3.5cms = 3.5cms
3 Platys @ 7cms = 21cms
3 Rummynose Tetra @ 5cms = 15cms
1 Scissortail @ 15cms = 15cms
2 Honey Gourami @ 5cms = 10cms
3 Cherry Barbs @ 5cms = 15cms
3 Black Widows @ 6cms = 18cms
2 Swordtails @ 11cms = 22cms
4 Zebra Danios @ 5cms = 20cms
1 Gold Sucking Loach @ 28cms = 28cms
2 Peppered Cories @ 7cms = 14cms
1 Molly @ 15cms = 15cms
2 RTB Shark @ 12.5cms = 25cms
3 Bengal Loaches @12.5cms = 37.5cms
3 Harlequins @ 5cms = 15cms
3 Bleeding Hearts @ 7.5cms = 22.5cms
4 Glass Cats @ 8cms = 32cms

Total = 393.5cms of fish. You are close to 4 times overstocked and if this tank has been running less than 6 months you are 8 times overstocked. To be honest I would expect you will start losing fish pretty soon unless you rehome the majority urgently.

You also have some fish that are too big for your tank, some that are incompatible with one another in temperament, some hard water, some soft water, and many that should be in shoals of six are being kept in groups too small, plus the Zebra Danios are temperate fish and don't do well at tropical temperatures.

There is no easy way round this other than to rehome the bulk of the stock, starting with the ones that will be too big/aggressive and the ones that don't suit your water, then move on to the rest.

hi james,
i have to agree with noodle on this,your tank is is beyond overstocked ive never heard of so many fish in a tank of that size.
my advice aswell is to dramatically thin out your stock and just keep the smaller varietys that are suitable to your water conditions.once you do this your tank will clear and the filter will be able to cope with the amount of waste produced.
hopefully once this is sorted you can enjoy a clear tank with happy inhabitants.
hope this helps and welcome to the site keep us posted on progress.
cheers
tez

Thanks for the replies guys. I don't think the overstocking quite as dramatic as that. I'm not saying it's not overstocked, by the sound of things it is. Your calculations are based on the maximum sizes of the fish, but many of my fish are nowhere near that size. My gold sucking loach for example is not much more than 10cm and seems to have stopped growing now. I'll try and work out how much length of fish I've actually got in there. I'm not saying you're wrong, if the recommended stocking density is 5cm per 4.5l I'm definitely overstocked, but I'm thinking when I work it out it may be more like 2 or maybe 3 times. Just goes to show that you can't believe everything you read, the website I went to in order to work out my tank's stocking capacity said it should be able to support 56 full-bodied fish or 92 slender fish. I probably should have got a second and maybe third opinion first. Oh well, I guess I've still got a lot to learn. Thanks for the advice!

You always need to stock based on adult sizes as overstocking will cause fish to become stunted due to lack of space, poor water quality and incompatibilty along with the presence of hormones from stock that cause stunting.

Most fish are sold as juveniles so the size they are when bought is no guide to size of accomodation needed which will be home for life and therefore suitable for them at fully grown sizes.

Using body-depth is part of the calculation, but it's impossible to stock a tank purely with that as a guide. A slim bodied fish 6 inches long will need more space than a full-bodied shorter one.

Other factors are their compatibility with one another - many of yours are not compatible, their need for a shoal of their own species, again, many of yours are too few in number, and their need for physical space for swimmimg. Your RTBs need at least four feet in tank length because the nature of their specific method of swimming can't be accomodated in smaller tanks.

The other aspect is water pH, hardness and temperature should be suitable for all occupants. Again you have a considerable variation in these.

At the moment I make it just over 200cm in total. So I'm definitely going to have to rehome a few. I'm not sure where I can find homes for them yet, and I don't intend to get a second tank. I'll have to think about that one. Which ones should I consider finding homes for? The water temperature is around 25 degrees. I can't give an exact figure for hardness, but I know it's pretty hard around here. I imagine the pH is fairly high, being hard water, but again I'm not sure of an exact figure. I'll see if I can get some test kits tomorrow and post the relevant info. I must admit it doesn't look crowded at all, and I'm thinking my plants may have something to do with this. A couple of them are getting quite large, so things may look a little different after some heavy pruning.

As it stands now the majority of your fish are best suited to soft-medium water, so best to wait for test results to make decisions in general, but there are some that need to be rehomed for reasons other than water hardness/pH.

Red Tailed Black Sharks - need a larger tank and become increasingly aggressive as they mature

Gold Sucking Loach - needs a larger tank, becomes very aggressive when it matures, will eat smaller fish when that starts to happen

Zebra Danio - needs cooler water

Scissortail Rasbora - needs a larger tank and a group of its own kind

Bengal Loach - needs a larger tank and more members in its group

Of the others, many need groups of six to thrive so consider whether you are willing/able to increase shoal sizes for those. If not, they should preferably be rehomed. This includes all Tetra species, Harlequins, Cories, Oto.

Beyond that things will depend on water test results. When you go to buy tests, please get liquid based test kits - paper test strips are so unreliable as to be next to useless. You will need to test the pH by running a cup of tapwater and leaving it to stand for 24 hours so temporay adjusters can gas off and give you a true reading. gH and kH can be tested right away.

Make sure to get tests for ammonia, nitrite and nitrate for the tank and post those results up as well as the hardness and pH of the tap water and we'll take it from there.

The API Freshwater Master Test kit is reliable and contains the basic tests, their kH/gH test is good too. Both are generally less expensive on eBay than in the shops, but essentially any reputable make of liquid test kit will be fine.

Derbyshire seems to be served mainly by Severn Trent Water.

Having just gone to their site and typed a random Derbyshire post code in, water quality results given are as follows:

pH - average (usually over a 6 month period) 7.47
GH - german degrees 10, so slightly hard.

Water Hardness (GH) : Terms and Conversion

mg/l CaC03 / oDegrees of Hardness / Described as:

0 - 50 / 0 - 3 / soft
50 - 100 / 3 - 6 / fairly soft
100 – 200 / 6 - 12 / slightly hard
200 - 300 / 12 - 18 / moderately hard
300 - 540 / 18 - 30 / hard
540 plus / 30 plus / very hard

You can just login, pop in your true post code to get a more meaningful reading

If that's the case then I'm afraid most of the softwater, acidic fish will need to be rehomed or taken back, including the tetra, gourami and oto of course.

The molly and swordtails are suited. Given they are livebariers are usually house as a 1M:2F ratio to stop the ladies being pestered.

Our care sheets here, give water param needs which will assist you

Given the Sharks need a min of 250 litres and will be aggressive as they mature with one another, these should also be moved on.

Hope that helps. Edit// apologies clashed with Noodle.