Constant bad luck with fish...?

* obviously your tank is cycled

Yes I have had this happen...

With fish dieing off like this I would check all levels. Ammonia, nitrites, perhaps even nitrates..

Are you using a water conditioner when you put new water in the tank? Chlorine is murder on fish health. It must be removed!

Check out this link. It has information on different fungal and bacterial infections. Pay close attention to the dead fish for splotches, dots, discoloration, ect. Even fish movement (when alive ;)

http://www.fishyou.com/freshwater/fwdiseases.html

Perhaps try a different fish... Something hardy like a school of small Barbs. Don't put anything else in the tank for a month or 2.

Maybe 4-6 Tiger Barbs to start. They are hardy and tough to kill off.

It's hard to tell exactly what you are doing wrong, but random illness is usually related to water quality. Have you actually tested the water to make sure how the cycle is running?

Maybe the medications have killed the cycle bacteria? Then your tank goes into a downward spiral of doom as the poor water conditions keep making the fish sick, and the medications stop the tank cycle from recovering. Some extra large part water changes may help, clear the meds from the system and freshen up the water (lowering the ammonia and nitrate levels) and lets thing recover and settle down.

Another thing I have found useful is to understock the tank, at least until everything gets settled down and running smoothly. The suggest fish numbers are for a well cycled and smooth running tank. You don't have that right now for some reason. Keep 1/2 the suggested number of fish and maybe it will settle down.

Also, sometime less care is better. Leave the tank alone. Don't change the filter, don't stress about the algae. Quick wipe of the glass, vac the gravel, change some water and otherwise leave it alone. Let the tank settle down and run naturally for a while and see what happens.

Lastly, as suggested, your fish may not all be compatible with your water. Maybe your water is in the middle and both would be OK, but check what you actually have. Keeping a fish way outside it's natural range can stress it, lead to random illnesses, over dosing with meds, and we are back to that downward spiral of death again.

Soft water with a low pH, stick to the tetras. Hard water and high pH, stick to the mollies.

Good luck and I hope you work out what the actual problems are.

Ian

We can try to help you, but you need to give us more info.

Exactly how many fish and type of fish, what are the results of tests for ammonia, nitrite, nitrate, and Ph?, how are you cleaning the tank? what size filter, Do you carefully float than acclimate the fish to the new water? What is the temperature in the tank? Are there objects in the tank that are not specifically made for aquariums? Are you overfeeding? Are you keeping schooling fish in proper schools of 6+? Is the temperature around 78 degrees and stable 24/7. Do you de-chlorinate the water? Are you adding chemicals other than dechlorinater,stress-coat, salt, maybe some melafix? if so that is probably not good.

Cardinal tetras need a low to neutral Ph, 6.5-7.0, mollies need a higher Ph of 7,5 or a little higher, these fish are not compatible.

female bettas need to be carefully added in a group of at least 5.

tetras need to be in a school of no less than 6, but only add 2-3 fish every 3-5 days. Also, these are sensitive fish that need a well established tank, not just a cycled tank.

Your tank may not be cycled. Most fish meds wipe out the good bacteria so the tank has to cycle again. Fish meds also weaken your fish's immune systems - like when your doctor gives you antibiotics for a cold. I would have a petstore test your water parameters because it sounds like ammonia poisoning. Dumping more meds in at this point is just going to make the fish worse unless you have a positive diagnosis.

Another problem may be that your fish need different water parameters. Both cardinals and mollies are farm-raised now so they can deal with water that is closer to neutral but mollies like slightly harder water and cardinals do best in softer water.

Edit: I just realized that you said the tank had been running a couple months. It tanks 6-8 weeks to cycle a tank and after that you are really only supposed to add 3 fish every few weeks or you overload the bioload. Both mollies and cardinals are too fragile for a new tank (less than 6 months old). At this point your best bet is to find a different petstore than the one you are currently using because they have been giving you bad advice, stop medicating the tank (you are going to lose more fish but adding medication won't help), buy a book on beginning aquarium care, test your water and do water changes, and just wait it out. It should sort itself out in about 6 months but don't add fish until then. If you lose all the fish then wait 8 weeks before adding more.

Luck has nothing to do with it. I agree with Joylynn, to a point. You need to go to a book store or library and get some beginner's aquarium keeping books. Read them thoroughly. You will probably find out you missed something crucial along the way. That is the best and only way to really learn how to have a happy, healthy tank. There are no magic potions or short-cuts.

You need a freshwater test kit (API master test kit is a good one). Learn how to use it and what the readings mean.

Your stocking choices are atrocious! Sorry, but Mollies need hard, brackish water, Cardinals need soft water, and Bettas do best in not-too-hard water. They like different levels of lighting and tank environments.

It sounds like fungus, but throwing in every medication imaginable is going to turn your tank into a toxic soup! You need to identify what your fish are dying from, and treat for that only. Take a water sample (and the dead fish, if you still have them), and go to a local fish store. Not some place like Petsmart, or any chain store. They know nothing. Seek out a privately owned and operated fish store. Anybody that makes this their life's work has a passion for it. The owner (and most likely all his employees) should know just about everything there is to know about fish keeping. They will have seen and diagnosed probably every common fish disease known to man.This will be your best resource while learning about your hobby. These guys love fish, love talking about fish, and love educating novices about fish. They will look at your dead fish, test your water, and tell you exactly what is going on. Repay them for their help by buying the medication they suggest (it usually doesn't cost too much, but if you just can't afford it, be honest. They may be able to recommend something cheaper that will still be effective). Also, help them stay in business by buying your supplies there. Things may be a bit more expensive, but that is because they can't buy in the massive volumes that chain stores do. What you can gain in knowledge and advice will more than make up for the slightly higher bill.

Word of caution: if you have Bettas in your tank, never, ever use Melafix, it is lethal to them! Good luck!

1. sometimes it's hard initially to learn to leave the tank alone

2. throw away any fish that are sick or show signs of illness, finish whatever treatment you are using and then give the tank a 30% water change

3. make sure you understand how to maintain the tank properly, especially how to avoid overcleaning the filter and how to siphon clean the gravel while doing your water changes

4. stop feeding for a few days a week

5. use only good water conditioners, like Amquel and Novaqua (some cause problems), don't try to use chemicals to change the water conditions

6. don't use any filter material that claims to remove ammonia (ammocarb, ammochips etc.)

I love fish too and it was hard for me to figure out what was the right thing to do as I was losing fish. This is what I found through years 20+ of experience, plus working at a pet store. The less you do to a tank the better; even changing the food will introduce new microbes into the water. It is like you living in you house for 10 years and then all of a sudden a door appears. You have to investigate it, see if it is locked, where does it go to...all these things changed your daily routine. Faucet water is horrilble for your tank. Try using distilled gallons. Yes, this water still needs to be treated to make it fish friendly but it is better than faucet water. If you have to use faucet water, pretreat it in a seperate sterilized container and areate it with an air pump and diffuser for at least a day..yes areation is a secret tip. The small pumps are very affordable. Never change water more than 40% of total volume. It sounds that you have used many chemicals to counteract your fish's sickness. Let's just start with this water and the secret is areation. You can never over areate your tank. Example: if your tank is a ten gallon an air pump saying up to 10 gallons is not enough. I would buy a twenty gallon air pump. See what I mean, buy your water pumps, air tanks, filtration devices for two times the volume of what you have. So, here it goes: Keep all your water in the tank. Add water when needed to fill the tank should it be low just this once with the pretreated water as described above. Purchase at the LEAST areation devices at least two times the reccommended size for your tank. Put a treatment in your tank as if it was to get the water 'fish ready'. Check the temperature make sure it is within reccommended guidelines. Areate the heck out of it for at least 5 days. Don't do or add anything to the tank besides check your temp or feed your fish (just a little). Over feeding is the main cause for tank problems. So, feed them once a day and count to twenty. If you have any food left over, too much! After the week of areation, your tank is still very fragile. Add one or two goldfish and let the micro-organisms that this fish introduces into the tank adapt the tank. Make sure you float any new fish for one hour and introducing an ounce of water into the fish's bag every ten minutes. When ready to put fish in the tank remove the bag, use a net and transfer the fish to the tank. You want the fish to get accustomed to your tank's water but you do not want to force your tank to get used to the fish's water. Your goal is to use your one or two new goldfish and create a strain of friendly bacteria in your tank which will make your tank stronger and will not be defeated by all these new strains of bacteria with each fish you add. NEVER add the new fish's water to your tank. Never add more than one fish per month. I know, I know...you want instant gratification, but I did too until I realized good things come to those who wait. I still have the goldfish I started with YEARS ago. Yes years! He is old, and fat and really friendly. He also is the size of a dessert plate! He is a very good fish to new comers and he is a testiment to how I have figured out the 'right' way to do aquariums. If you get an algae bloom, or smokey looking water do not fret, it is part of the cycle to establishing a tank. What people do not understand is the person could have a 'forever new' tank that has been up and running for months. The don't give the tank time to mature it's water and develop it's friendly bacteria by not doing anything to it...nothing. It does say on many products just add this and the water is fine. Well, you can eat cake batter too and it is a cake but not really, right? Same concept. Let me know how it is going . Please do not hesitate to contact me with questions. I know it can be frustrating but I promise follow my steps. My email is Iisshe33@mchsi.com Good luck and thank you for wanting to make your fishes lives the best that they deserve. Life is precious no matter how small the creature is. Good Luck!

Not exactly, but would love to comment. My Uncle, in New York city had tanks with very expensive, & beautiful fish too. It gets to be an "expensive hobby" he told me. *(of course if one sticks with guppies, gold fish and the simple types of species. it's different. They actually do eat each other too! Lots of work, pumps do break, or just stop when we have incumbent weather conditions caused on our electrical resources. (Good to have a generator here) One should probably do a lot of work on "reading first", due to the initial cost of a tank and all the equipment it requires...I have always had a "secret wish to start an aquarium", myself.. but never the time to do that initial reading first. One must think of the water system; replacing broken or just "out dated pumps/equipments, foods and medicines, * ("yes they need that too!) and which specific fish who do well with whom? (there are real rules on that one), and of course if one decides to expand the collection, that's more tanks, or adjustments. Put in lights and decorations in the tank, it all costs.... (The added time and expense that would take to up keep all this is working well, is important also.)

Does it look like, cryptocaryon? I take it you are not over crowding. Some fish like female bettas can be very territorial and mollys like to nip at long fins. Maybe you need some kinda anti fungal. Other things just to check though is water pH or water temp.

well i do know that when you have any type fish you have to let the water set 24 hrs before putting them in the tank or a fish bowl. when you bring home your fish in a plastic bag have your aquarium set up and lay that plastic bag in the tank for a couple of hours turning it occastionally.. i hope this will be helpful and u may already know that so excuse me if i insulted u didn't mean to just trying some different tecniques for u.. if u have a water well then u need to use bottle water