I have just started my aquariam for the first time( i am new to this). The shop suggested i bought 6 neon fish to start with. I did this about ten days ago. Now i only have 3 left....is it possible they are eating each other? i can not see any dead fish and one neon is slightly larger than the others. Any suggestions?

OK, first thing's first, how long has the tank been set up?

By the term 'Neon fish' I'm assuming you mean Neon Tetras (Paracheirodon innesi).

Although Neon tetras are related to Piranha (they come from the same family, Characidae) and they do posess a set of small, razor-sharp teeth; it is highly unlikely that the fish have been cannibalizing eachother. I would suspect poor water quality as the primary cause of the deaths.

Poor water quality in new tanks is usually as a direct result of not cycling the filter or cycling the filter inadequately. High levels of ammonia and nitrite in the water after the fish are introduced are tell-tale signs of NTS or New Tank Syndrome. Do you have a test kit? If you can answer yes to this, can you provide the test results for pH, ammonia, nitrite and nitrate.

All fish produce ammonia as a by-product of their own metabolism (very similar to human physiology, where ammonia is also a by-product of cell respiration and is excreted via the urea) and is excreted via the gills. This ammonia is highly toxic to aquatic organisms even in small concentrations and its toxicity increases with pH and water temperature.

When fish die, the bodies decompose rapidly and this process is expedited by the other fish, which will nip and tear away at the flesh from the corpse. This may sound gruesome, however this is the nature of things and in the wild this is vital in order to maintain a healthy ecosystem.

what Chilly said

on top of this, neons are far from a hardy fish, and the shop was very wrong in suggesting them as a first fish.
they dont usually do well in tanks that are less than 6 months old, because they are highly intolerant of changes in water chemistry, which happen more frequently the younger a tank is, especially if the tank has not been matured fishlessly for a month or so before they were added!

the tank had been set up for about ten days before i added the fish. What is the name of the kit i can purchase? Can you tell me more about the kit or maybe it will come with guidance? I have not changed the filter yet as my start up guide suggested every 4 weeks and that time has not lapsed yet. I have not/can not see any evidence of dead fish. What should i do to keep the remaining three alive?


What fish should i have started with?

Thanks so much for the advice. Much appreciated.

Just as I suspected, the tank hasn't been cycled properly, no doubt due to incorrect info in the start-up guide supplied with the tank. With all seriousness, condemn this 'guide' to the nearest trash can now before you lose anything else.

You need to wait a few weeks before adding fish to allow the filter to 'cycle'. The term 'cycle' is derived from the biological process known as the nitrogen cycle, which in its fishkeeping format is where ammonia produced by fish and decomposing waste and food is broken down into less harmful waste substances by a colony of friendly bacteria which colonize the filter.

If you don't cycle the tank, the filter won't be able to deal with the sudden increase in fish waste and as a result, the levels of toxic ammonia and nitrite (what's formed after ammonia has been broken down) will skyrocket. The result is of course poor water quality and dead fish.

The test kit I refer to is a master liquid test kit, which you can buy from all good aquatic stores for around £20. The test kit will have test reagents which adjust the colour of the water samples in test tubes according to the concentration or level of each parameter (i.e ammonia, pH). The colour of each test sample is compared with the relevant colour chart (very much how urine glucose-testing strips work).

DO NOT replace any of the biological filter media (this includes sponges and any ceramic rings or balls), as that will simply send you back to square one where cycling is concerned.

Why the hell manufacturers continue to give out this information I've no idea...

The test kits you need are as Chillinator has said and sold under various brand names Tetra, Interpet and a number of others, he prefers the liquid ones I prefer the tablet ones.
When you set the tank up the ammonia levels will rise and as the bacteria start to colonise the filter it will drop suddenly as the ammonia is converted to nitrite by the bacteria. The nitrite levels will then rise and will then drop suddenly as diiferent bacteria colonise the filter and convert the nitrite to nitrate. The nitrate will then rise and is kept to acceptable levels by partial water changes.
Obviously if you change the filter at 4 week intervals you will have no bacteria to convert all these toxins.
I keep a reef system with no filters and so am not upto date with what is on the market for tropicals but if you let us know what tank and equipment you have someone will advise you further. If you let us know what area you are in I am sure someone will be able to recommend a shop that will give you good advice when you are buying stock.

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i have a biorb tank (60litres)... There is a sponge filter and i was told to change it very 4 weeks but now im learning this is not correct.. should i take it out at all even just to run it under the tap or not?

So my situation now is that i have 3 neon tetra.. should i change the water and hope these wee ones dont die? If so how much and how often?

How often should the filter be changed?

When should i consider adding more fish?

you should never, under any circumstances, run the filter of any tank under the tap. tap water contains chlorines, heavy metal traces, and other nasty stuff. this is what makes the water safe for us, but its deadly to filter bacteria, so if you wash your filters under the tap, you will just be killing it all off.
however, the filters do still need washing occasionally (around once a month or so), and to do this, simply remove them from the tank, and squeeze them out in a bucket of old tank water. usually best doing this during a water change, so you can use the water removed from the tank.

the filters wont really need changing all that regularly, far from as regular as the shops will say. if you really must change them, id say maybe replace half very 6 months or so. this leaves the other half in place to seed the new stuff.

at the moment, as the chemicals in your system wil be going doolally, your gonna have to be doing some big regular water changes to keep the levels as low as possible. probably about 50% every 2 days. this is to remove the waste from the tank that the filter bacteria would normally remove. if its just left, then the waste levels would rise dramaticaly, and you will experience further losses. and onot under any circumstances add any more fish until you know the tank has cycled. this means your tests will show no ammonia, no nitrite, and will show traces of nitrate.