Disappearing Neon Tetras and how I keep my tank clear.

[FRANKLIN BLEVINS]

Howdy folks, newbe here so I will manage to bust the forum ethics on the first go no doubt.

So I have an aquarium (duh) and I had 4 neon tetras, they seemed rather healthy and nice to look at so I bought 4 more for a total of 8 (math still works). Right away I noticed I was down to 7 but could not locate a missing or dead fish, then just as quickly I was down to 6, then 5 and then back to what I am guessing is maybe the original 4 and then just as quickly as the mystery started, the number remained and remains at 4. Where did my fish go? I never discovered the bodies.

OK for years I battled cloudy water issues with my tank and then I stumbled on the cure and have had clear water ever since, going on two years now. The answer turned out to be very simple. Every time I feed my fish, I pull the filter out of the unit and wait until the fish have fed and then put the filter back. Since my filter cartridge slides out of the slots in the main unit, it is real easy to pull it out and lean it against the housing without spillage. That appears to be the number one cause of my bacteria blooming and I now enjoy clear water all the time. The only downside to having clear water is that it lulls you into a false sense that your tank is doing fine and does not require any further actions, but of course you still need to change out the water and make sure the temperature and other balances are maintained. I have been guilty of leaving the water unchanged for longer than is recommended, only adding water to maintain the water level.

I do have casualties along the way, fish die, no getting around that, but the disappearing Tetras has me baffled. Here is my basic occupants. 2 Cory catfish, 1 sucker fish (standard issue type) 1 Gourami, 2 neon Danio's 4 neon Tetras, 2 guppies and one orange platy in a 20 gallon tank, I do use a little salt in the aquarium per instructions, so far they fish seem healthy with only the occasional casualty.

Any theories on what happened to my little neon's? I have read around and I guess the usual reasons are probably why but hey, maybe someone knows about the neons...schooling number limits?

 

[Byron]

Welcome to TFF.

I will not guess as to the cause of the neon tetra deaths (assuming they died in the tank...did you check for them on the floor? all fish can and will jump if openings allow). But once dead, it does not take long for a small corpse to disappear. Fish will sometimes eat them, snails if present, and of course various bacteria.

The main issue here is too many species in a small tank. Tetras, danios, and cory catfish are all shoaling species that must have a group, and while more is always better, five cories and six or seven of the tetras and danios would be minimal. I'm not suggesting adding more, just pointing out the deficiencies which do impact these fish negatively.

Salt...never use salt in a freshwater aquarium on a general "add a little regularly" basis. This is harmful to fish. Salt can be effective as a specific treatment for certain disease/issues, depending, but never otherwise on a permanent basis. It is not usually easy for any of us to see that a fish is not really at its best, unless it becomes so serious the signs appear by which time is it often too late to rectify. Fish can struggle for weeks and months under inappropriate conditions, then suddenly they give in and weaken, or sometimes they may become increasingly aggressive.

 

[FRANKLIN BLEVINS]

Welcome to TFF.

I will not guess as to the cause of the neon tetra deaths (assuming they died in the tank...did you check for them on the floor? all fish can and will jump if openings allow). But once dead, it does not take long for a small corpse to disappear. Fish will sometimes eat them, snails if present, and of course various bacteria.

The main issue here is too many species in a small tank. Tetras, danios, and cory catfish are all shoaling species that must have a group, and while more is always better, five cories and six or seven of the tetras and danios would be minimal. I'm not suggesting adding more, just pointing out the deficiencies which do impact these fish negatively.

Salt...never use salt in a freshwater aquarium on a general "add a little regularly" basis. This is harmful to fish. Salt can be effective as a specific treatment for certain disease/issues, depending, but never otherwise on a permanent basis. It is not usually easy for any of us to see that a fish is not really at its best, unless it becomes so serious the signs appear by which time is it often too late to rectify. Fish can struggle for weeks and months under inappropriate conditions, then suddenly they give in and weaken, or sometimes they may become increasingly aggressive.

Fortunately, the fish that require more than one have at least two. Well, at least I have a credible direction to go once the numbers dwindle down a bit. I think my platy is probably on its last fins. Just curious, is there a general number of fish I want to limit for a 20 gallon tank? I will take your salt advice to heart. I had never heard of adding salt to a freshwater aquarium, but the internet suggested otherwise so I ran with it.

 

[Byron]

Fortunately, the fish that require more than one have at least two. Well, at least I have a credible direction to go once the numbers dwindle down a bit. I think my platy is probably on its last fins. Just curious, is there a general number of fish I want to limit for a 20 gallon tank? I will take your salt advice to heart. I had never heard of adding salt to a freshwater aquarium, but the internet suggested otherwise so I ran with it.

There is a lot of inaccurate and/or misleading "information" online; one has to know the source of the data, by which I mean, who precisely wrote it. I know personally or by reputation who can and cannot be relied upon. If you want the low-down on salt, what it actually does, I explain it in my article posted here:
http://www.wetwebmedia.com/SaltArtHosking.htm

Fish for a 20g...there is no way we can suggest a number of fish because it depends upon the species and their requirements. I will digress a moment to briefly explain what has to be considered in putting together a community aquarium (one containing more than one species of fish). Obviosly the size of the mature fish, and the space they need to be "normal" in behaviours, interactions, swimming, etc. Shoaling fish must have a group if they are to be healthy so those numbers hbave to be considered; it is not really surprising that fewer fish of a shoaling species actually can have more impact on the tank's biological system, simply because the effect of not providing the necessary numbers of the species causes trouble for the fish, and this results in the fish making more impact on the system. All of this is nothing we can see, we simply know it occurs and have to provide accordingly. The activity level of one species may cause stress to a sedate species (the reason for no danios or barbs in with sedate fish like gourami and cichlids) and this impacts the system more. Inappropriate aquascaping will cause stress, another impact. The wrong water current from the filter can stress out fish, more impact. More filters or larger filters never increases the tank's capacity, it is the species themselves and their requirements that impact.

A simple example: 20 zebra danios would be too much in a 20g tank, but 20 cardinal tetras would be fine. The danios by their very nature, even though pretty much the same size, have more of an impact biologically than do the sedate cardinals. Assuming the cardinals have the aquascape they need to be "happy."