I have a freshwater problem. I know this is a marine site, but everyone here seems to be very knowledgeable and it's the only place I know where to go. I have a 5 gallon hexagon tank and it did have about 6 fish each about 2 inches(2 tetras, 2 guppies, zebra danio, algae eater and frog). The zebra would constatly attack any of the fish even though they were bigger than him and fish were fallling one by one until now I have him, a guppy and a tetra. He just chases them though. Are they dying of stress or is my using tap water affecting freshwater fish?
P.S. Three fish have dyed while my light burned out its been out for a week. Do they need the light for survival?
Any help highly appreciated.

I haven't kept freshwater for 20 years but I seem to recall zebra danios zipping around the tank but not attacking other fish. What are your water parameters? Are you using a water conditioner or just straight tap water?

I had a few zebras and they were horriable, really mean to everything else. Your water could be the cause...hard to tell. Take it to your LFS and get it tested. Also is your tank cycled? How long has it been up and running? Do you use a heater? lastly, the light shouldnt matter espically for only a week or so.

12" of fish in a 5 gallon aquarium seems like quite a bit of biomass. I usually figure 1" of fish/gallon in freshwater. I do go over that a bit in my heavily planted 10 gallon tank, but the fish have lots of plants to hide in, and I've chosen very peaceful fish. (One betta, guppies, tetras, algae eater)

And I do remember the zebra danios being very hyper-active when I tried them years ago. I haven't added them to my 46 gallon yet because I think they'd drive the other fish nuts. :) If it was my tank, I would remove the zebra, and add at most 5 small tetras.

Tap water should be OK, but it depends on your tap water. Treat it for chlorine, equalize the temperature, check your tank water for PH, ammonia, nitrite, nitrate, KH, GH. Do weekly water changes. The fish shouldn't need the lights to survive, but any plants you have will.

Tell us more of what you want to accomplish with the tank and we'll be able to help better. I belong to some good planted tank forums, if you're interested.

Zebra Danios and Danios in general, are a very active fish that congregate in large numbers in their native habitat. With plenty of space to roam, ample food and good water conditions, Danios are an interesting fish to keep. However, a single Danio in extremely crowded conditions such as your 5 gal tank will be stressed to the max causing the behavior you describe. This places maximum stress on most tank mates and stress leads to death through disease, and/or organ failure, like heart attack. Think of yourself locked into a closet with six of your friends. Even given ideal living conditions, that closet would turn into a living hell. That's what you have provided your critters in the 5 gal "closet".

liquid wind welcome to the site bud, & dont worry about the non salty related question, all friends here! I'll give you some bread crumbs if you like, that way you can change the name to follow-thru / turtle necken rather than liquid wind :D

Seup , welcome as well, always nice to see fresh stocks join the ranks.

LiqWind whats the story with the frog, real frog of fish variety?

These guys have it covered, no need for my input cause they have already asked fundamental questions in order to prop help you.

It is straight tap water. My dad has a RO filter hooked up to his sink would that help?(and would it be good to use in a marine aquarium?) Iv'e been tossing back and forth selling the remaining fish and buying a fig 8 puffer, but don't know how big they get when fully grown. Also the algae eater was the 1st to go would him cleaning less have been a cause because you can visually see the difference faster?

Whether fresh water or salt, rule number one research, research, research before you buy anything. You have a 5 gal aquarium. Please reread my post above.

Liquid Wind: RO is definately better than tap (RO/DI is best, and a necessity in a reef tank IMO), but whether you need it or not for a freshwater tank is somewhat dependant on the water quality in your town. Perhaps a knowlegable and reliable LFS could advise you about this. As far as the behavior issue, It sounds more like the Danio is just not happy, and maybe he should go back to the LFS before he stresses everyone out (including the aquarist!).

Suep: What are some good planted tank forums. I'm tinkering with the idea of using my now defunct 10 gallon aquarium to start a planted tank.

Here are some planted tank forums that I keep an eye on. There are many ways to succeed with a planted tank, from high light/high tech, to low light and very little tech. Diana Walstadt, with her El Natural Method, likes using natural soil and does almost no water changes! Like anything else, you need to decide what your goals are and then study, study, study... I'm no expert, by any means, but my 10 gallon (The Jungle) has been doing well since last May and I'm setting up a 46 gallon.

Aquarium Plants and the Barr Report - Aquatic Plants (http://www.barrreport.com/)

Aquatic Plant Forum (http://www.aquaticplantcentral.com/forumapc/)

I tend to use low light, I use Seachem's Excel as a carbon source and the other Seachem fertilizers, and I'm just starting to experiment with Tom Barr's EI method of fertilizing. I may end up going with pressurized CO2 on the big tank but I'm hoping I don't have to.

If I can help anybody, just send me a message here or via email. I really believe we learn from each other and I'm very grateful sites like Talkingreef exist (and my reef tank is grateful also!) :rolleyes:

Thanks for the info suep, I'll check into these forums.

Thanks for the help guys, but I may start a saltwater aquarium and as I understand the RO water from my sink would be suitable for a FO tank? The danio is still zooming around like mad and I will probably return him and the remaining 2 for a figure 8.

if your talking about a figure 8 puffer, do a lot of research first, if i remember right, your looking at a brackish water fish, and a minimum of 29 gallons. happy hunting