Fish mysteriously dying

My sister is running a 10 gallon tank with only guppies in it for the past two years. She has been having problems with the fish suddenly dying.

We have brought her tank water into our local pet store that specializes in fish and the water tested perfect for guppies. The water is clear and does not smell.

We just picked up some more guppies Friday dec 6 and all of them have died. The weird part is that her guppy that she raised from a fry is still alive.

The fish just before dying would lie at the bottom of the tank and would appear to be lying on their sides, or would be suspended vertically near the surface of the water just before dying.

My sister does 10-15% water changes weekly with a gravel vacuum. She uses ClorAm-X to treat her replacement water and lets it sit over night before doing the water change.

She does have what looks like white, stringy algae on the sides, decor, and gravel (1/4" deep) of her tank, and when you wipe it off it is brown in colour.

We just picked up a new aquaclear filter and jager tank heater dec 12.

Her previous tank heater cracked and seemed to be leaking electrical current into her tank and the aqua-tec filter was not doing a very good job of filtering the water.

She does not over feed the fish, but did have an over feeding problem in the past.

WELCOME!well for the new guppys they could have possibley came with a parasite or could handle the stress from moving from tank to tank. i would look at the forum BROWN ALGAE for info on the the white things

Good advice! The next time you add fish, try using the drip acclimation method. A full description is in the blog section, or it's under tips and tricks.

A ten gallon aquarium is pretty small, so any over crowding or over feeding will have a large impact very quickly. For a week or so, you could try more frequent, slightly larger water changes to help clean up the tank. This is just a guess, but another inch or so of gravel may give the beneficial bacteria more living space.

animefan93 wrote:

WELCOME!well for the new guppys they could have possibley came with a parasite or could handle the stress from moving from tank to tank. i would look at the forum BROWN ALGAE for info on the the white things

The fish came from a breeder and all their fish are healthy, and the breeder's set ups are very clean.

The only possibilities that we can think of is that the tank heater was leaking current into the tank, killing the fish. Due to the glass being cracked at the back, where you would never see it unless you pulled the tank out.

This has been an on going problem for the past couple of months. The fish will be fine for month or two then just die, even her fry.

The breeder told my sister that her tank sounded like it did not have enough hiding places for the fry and the adults were eating the fry and dying. So we purchased a bunch of aquarium approved plastic plants, but never got them into the tank before the fish we bought on the 6th all died, but no small fry where in the tank at the time for the adults to eat them.

After doing some reading I came across a post saying that rust could cause fish to die. The screws that held the flashing, for the lights, to the aquariums lid rusted and the lid always has condensation on it. May that be a cause, the particles of rust dropping into the tank?

The last possibility was that the water was too much of a shock to the fish and they died as a result or we just placed too many new fish in the tank at once causing an ammonia overload. But the ammonia overload would have killed all of the fish, wouldn't it, including the one she raised from a fry?

I was thinking of getting 1 or 2 Otos for the tank to assist with keeping the algae down. You can barely even see the algae unless you are really looking for it.

The I acclaimated the fish to the tank using the plastic bag floating for about 20 minutes then adding some water from the tank to the bag for another 30 minutes. Then emptying the bag into tank.

Live bearing fry hide in live, floating plants like hornwort or water sprite. Even if the fish you got from the breeder were perfectly healthy, the float and dump acclimation method could have been a shock which compromised their immune systems. Drip acclimation causes much less shock, is easy to do, and takes about an hour. Of course, the fish that were already acclimated to the aquarium would not be affected.

A little bit of iron oxide will not kill fish, although you should never use a busted heater. Regular partial water changes will remove most dangerous chemicals. Please do not add any more fish; that will just increase the biological load. If you do regular partial weekly water changes, you should not have a problem every two months.

I hope some of this helps. Please let us know.

Right now all that is in the tank is the lone guppy.

I am going to wait until after Christmas to get anymore fish for my sister. That way I will be able to monitor the tank while I am home during the school break.

When I do pick up more I will most likely get two Otos and use the drip method to get them ready to go into the tank.

I am away at school, so my sister always calls me to let me know what is going on with her tank. When I was home on Dec 11 I gave the tank a good look over and noticed the crack in the heater. I removed the tank heater right away and had it replaced by 3:00 the next day.

Welcome to the forum!

I'll add my 2 cents and say that Bristlenose Plecos are Excellent little algae eaters, and a lot of the time they are out and visible. They're always working.

I have to say that hands down the drip acclimation method is highly preferred. It's so easy, and cheap... A clean bucket or two and some air hose... And it's SO much less stressful on the fish.

I'm concerned about the white stringy things... Can you or your sister get a good look at them? They could be hydra or nematodes... Both of which are a pain in the tank.

Also... if there are changes in the tank, the guppy that was already there... it's got to be tough... being the only one left... It might be strong enough to take a slight ammonia spike... Where the new comers... They're trying to get over the stress of being caught... Bagged... Floated... Dumped... etc. I know that my rainbows... even just moving from tank to tank here... They'll dull out in color for a day or so... The stress is bad on them. But you have to bring the fish home... You just have to be prepared to do the best you can do.
Hope the lone guppy does ok.

We did have a Pleco in the tank about 2 months back, then it along with about 4 guppies all just died after being in the tank for about two months.


This has been an on going process for my sister.
The most fish we have ever had in the tank at one time was 10 neon tetras. Since they all past away due to water temperature problems. We have never had more than 8 fish in the tank at a time.

My sister loves to keep fish, but has been having difficulty since she moved from keeping bettas to keeping fish in the 10 gallon aquarium.

I try to assist her as much as I can, but my specialty lays in the care of Crested and Leopard geckos.

OMG i just bought two baby leos and i love them so much and crested geckos are so cool looking too but expensive. ok i think i may have bought two males about at what age to you think they would start to fight?

Animefan93 I sent you a PM on the geckos.

I have 2 leopard geckos and 4 crested geckos. They are so easy to care for and provide some good amusement when you catch them doing strange things.

After reading through your posts again, I just realised that it sounds like you have a metal hood directly over the water. I hope that's not the case, but if it is, please buy a glass cover to go between the things. When electricity flows, water to metal contact is dangerous, although it probably does not bother the fish.

Before you restock the aquarium, try a couple of large water changes to get rid of all the chemicals and bad cooties. I still think some of your problems are due to over crowding or over feeding without regular maintenance. Ten gallons is not much water, so it's difficult to keep things balanced, especially with a maximum biological load and no live plants. In my opinion, ten neon tetras are way too much for the tank. It may be best to start with one male and two female guppies. If the fish and aquarium are healthy, in six or eight months you'll have plenty of guppies to give to your friends.

johnarthur wrote:

After reading through your posts again, I just realised that it sounds like you have a metal hood directly over the water. I hope that's not the case, but if it is, please buy a glass cover to go between the things. When electricity flows, water to metal contact is dangerous, although it probably does not bother the fish.

The hood is plastic, but there is metal flashing that redirects the light into the aquarium, just above the bulbs. The aquarium is one of the Aqua-Tec kits that you pick up from wal-Mart for $50.

If there is no glass between the water and the electrical sockets and/or other connections, you have a potentially dangerous situation. The electrical current will not go anywhere unless it has a flow path. In other words, the aquarium water could be at 115 volts, but nothing would happen until you furnished a partial ground by putting your hand in the water. If you did it when your body was solidly grounded, you'd get a pretty good zap. I know all this because it happened to me several years ago. Talk about a surprise when I sucked a little too hard on the syphon hose

Some plastic hoods have a plastic sleeve around the light socket, but water condensation can still be a problem. Maybe the Aqua Tech kit has additional safety features. It's worth checking. Please let me know if the partial water changes help.

After running the Aquaclear filter on the tank since my last post all of the algae in the tank has disappeared. I can see no signs of it on the glass or the gravel.

No fish have been added to the tank either. Right now the tank is just running empty, the one fish that was left has disappeared and can not be found anywhere.

Before you add fish, it may be a good idea to test for ammonia. The test kits are inexpensive and easy to use. Did you buy the guppies directly from the breeder, or did they make a detour through the pet shop? Quite a few pet shops have a central filter for their aquariums, which means that all the fish are swimming in the same water so they share diseases and parasites. Usually, a fish's immune system can handle most diseases and parasites, but the shock of moving them to a new aquarium can compromise their immune system. It can take several weeks for a problem to show any symptoms.

johnarthur wrote:

Before you add fish, it may be a good idea to test for ammonia. The test kits are inexpensive and easy to use.

I will look into that for my sister. All the other times that we have had it tested for ammonia the tests have come back fine.

Did you buy the guppies directly from the breeder, or did they make a detour through the pet shop? Quite a few pet shops have a central filter for their aquariums, which means that all the fish are swimming in the same water so they share diseases and parasites. Usually, a fish's immune system can handle most diseases and parasites, but the shock of moving them to a new aquarium can compromise their immune system. It can take several weeks for a problem to show any symptoms.

The fish are bought from the breeder directly. The pet store that I do my business from uses individual filters for each of the tanks in the store, except for the feeder fish tanks they are filtered together.

It sounds like you bought healthy fish, so something in the aquarium must be making them sick. The usual culprits are too much food and too few partial water changes, but you apparently have that covered too. A similar thing happened to me several years ago, and it turned out that the dechlorinating drops I was using had lost their effectiveness, probably from old age or heat. Now I buy Stress Coat by the gallon, but there are plenty of other good water conditioners on the market.

Have you added any new plants or decorations in the last several months? Both can carry parasites and diseases, and decorations not made specifically for aquarium use could release toxins into the water. Another source could be spoiled fish food or wild caught live food. Fish food doesn't necessarily smell good, but it also shouldn't smell awful. In addition, frozen food should be well thawed. Maybe it's none of those things, but it almost has to be something that's entering the aquarium. Please let us know what you find out.

johnarthur wrote:

A similar thing happened to me several years ago, and it turned out that the dechlorinating drops I was using had lost their effectiveness, probably from old age or heat.

Could there be a possibility in the dechlorinator lossing its effectiveness. The dechlorinator is kept in our kitchen and the wood stove is almost right below where the drops are kept. But it does not really explain why the tank will be good for 2 months or so then all the fish just die and the cycle will repeat itself.

I'm interested in what John has to say about this one...

I am in no way a fish "expert" but here is what I have come to learn about aquariums and how I set mine up.

I first washed out the tank with only water. Then I washed all of the gravel, plants, heater, filter, etc before putting them in. I let the tank sit with 100% water for 48 hours and after adding a teaspoon of Bioshock I took a sample to Petco, where everything looked Perfect, the only think being the water was a little alkaline. This is normal, so I bought PH tablets. After putting the fish in (I have a 10 gallon tank) I immediately dropped in 1 PH tablet, 2 teaspoons of aquarium salt (coats the fish gills so they are less susceptible to disease). I then fed twice a day and kept the water in between 72-82 degrees. I do not understand what your problem would be unless the fish were either:

a. getting electrocuted through the subsonic electrical currents generate by the heater.

b. were overfed/underfed

c. were purchased with unknowingly harfmul parasites or viruses

d. were exposed to the aquarium without proper gravel washing, plant washing, etc.

Hope this helps in some way.

When the chlorine drops went bad on me, they did not lose their effectiveness all at once. The fish seemed to be fine for quite a while, then they just died much like you described. The drops were probably a few (?) years old, and they had been stored inside, although here in Phoenix things can get very warm. The bottle of Dechlor was fairly large because I had several aquariums. See if you can talk your sister into putting away the chlorine drops and getting a small, inexpensive container of water conditioner. You might also make sure she is keeping up with maintenance chores and not over feeding.

Again, please keep us posted.

She uses Hikari's ClorAm-X, which removes chlorine, chloramines and ammonia. When I read the bottles that are available from my pet store one says water conditioner and the other says dechlorinator. Yet the labels say the exact same treatment is provided by the product.

Do you have any recommendations for which product she should use? She was using Aqua-Plus water conditioner, but was having the same problems with the fish dying.

She never had problems with bettas so maybe I should get her some female bettas to put in the tank.

Right now my sister is just happy with the water filter running making the sound of falling water,. I think she just said taht because she is tired of losing fish.

Stress Coat and Amquel Plus are available in small bottles. That may not solve the problem, but it's an easy, safe experiment. Hikari products are usually very good, but if the dechlor is out of date or if it has been exposed to too much heat, it can fail. To make sure all the toxins are cleared, change 20 or 25 percent of the water every day for about a week, then go to a once a week schedule. Just those water changes may clear the problem, but if a toxin, disease or parasite is still in the water, the problem will keep coming back until its source is removed. Without looking at the aquarium, I can only guess that the toxin may have entered through a leak patch, a rock or decoration that shouldn't be in the aquarium, too much or inappropriate food, contaminated gravel, bug spray, furniture wax , etc. I say toxin, because something can leach into the water and kill the fish slowly. Of course, the something includes chlorine. Let me know if any of these guesses help.

You know... that brings up an interesting point John.

If you are a neat freak... Or have considerably more free time than I do... A lot of people clean the outside of their tanks...

Now if you spray... say... Windex, on the tank and then wipe it off... If your tank doesn't have a REALLY tightfitting top... Then some of that Windex is going to get into the water... There's a lot of Ammonia in Glass Cleaning products...

It's just a thought.

In the very rare occasion that I actually clean all my glass... I spray the bottle in the kitchen, away from my tanks, onto a paper towel... Then I rub the sides of the tanks with that cloth...

It may be something crazy simple like that...

Just a thought...

if you decide to get female bettas make sure you get more then 3 or they will fight nonstop and kill eachother...they will rip eachother up at first but stop fighting after they have domince levels but will still flare at eachother a lot but the more there are the less they fight. right now i have about 6 females in a 29 gallon tank but could have a good 10 or more in there together. so with a 10 gallon you could put 5 or so in there together and the females can be just as nice looking as any male

I converse a lot with the pet store owner where I get almost all of my pet supplies and he has a good knowledge in fish keeping and he told me to ask my sister if she was using any cleaners, personal care products, or smoking where she keeps her tank. The anwers are all 'no' she does not use any aerasol cleaners in her tank nor does she use any perfumes in her room.

While we're on the subject of cleaning, a mild solution of white vinegar in water in a spray bottle is good on exterior aquarium surfaces, and it's not toxic if a drop or two happens to hit the water. Even we sloppy freaks have to admit that clean glass is easier to see through.

I have been thinking of removing the plastic plants and getting some real plants for the tank. The two that I have considered are java moss and duck weed. The plants need to be able to grow without a lot of light because as of the moment I have removed the lid that was currently on the tank and am looking for a new one to purchase. I think that I may purchase the perfect-a-light hood.

Another thing you can do, is purchase a glass top, which will aid in the preventing of evaporation.

Then you can skimp on the light... You can go to lowes or Wal-Mart and grab a rather cheap under the counter light, or whatever you can find.

If you want the look, you can just buy a strip light. Instead of the complete hood.

It will save you in the long run. There's nothing like a glass top.

Also, I'm back to reading again, and I've read that more plants is better, so if you can get a large amount of plants, the chance you'll do well with them is better. In the past, plants have been so expensive, I've just bought a couple. Well they usually die, and make a mess in the tank, having rotting plant matter... So lately, I've gathered up more plants and filled the tanks up, and they're doing SO much better!

I'm not a plant specialist, and never fooled with CO2... but just a thought.

Good Luck!

Most of the hoods you buy from aquarium shops have single tube lights, which are fine unless you want exotic plants. Probably you should assume that low to moderate light plants are the best, although they grow slowly. Other plants require intense lighting and carbon dioxide systems. A clay based substrate like laterite will help provide the minerals that plants need. An easy, cheap floating plant like hornwort will improve water quality.