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HUGE MOLLY AND POSSIBLE TANK DISASTER !!!!!

3K views 12 replies 5 participants last post by  bettababy 
#1 ·
All Mollies dead in 40 gallon tropical aquarim tank. I know i know i hear it over and over agian these fish are brackishwater fish and well there was some salt about 3 table spoons in 40 gallons of API aquarim salt. anyway i did a water change today i did a 10 gallon swap cause the water looked a little cloudy. that happened 2 hours ago now the water i put back in was aged 24 hours and was the same temp as the tank and had tertra aqua safe decholrinizer in it. i kept the water warm using the same brand stealth heaters as in the tank to ensure no difference and i checked before putting the water in. so anyway 2 hours after the water change i go down stairs and 4 out the 6 of my mollies are dead. the other two are not looking so hot the rest of the tank is fine and acting normal
2 angels
2 paradise fish
2 swordtails
4 platties
2 black skirt tetra's
4 cories

water parmaters
nitrate 20
nitrite 0
ppm hardness 50
ppm alkalinity 120
ph 7.1
temp 78
salt 1 tablespoon per 10 gallons

tested with api liquid master


sorry this post is so long i wanted to be priciese wat should i do with the whole tank i need suggestions all the fish looked normal when they died i looked at them carefully no outside signs they were having a problem

the mollies that died were
2 white sailfin mollies (male and female)
1 sunset mollie (female
1 ballon body (female)

the 2 that are still alive
1 sunset mollie
1 balloon body molly

ill post pics in a minute

please tell me what i need to do
 
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#2 ·
Well from what you have said my first thought would be you need to get a hydrometer. I made this mistake when I used to add salt and killed a few fish with a water change.

Large swings in salinity can be the worst thing for them. A hydrometer will help you make sure that the water you are putting in is the same salinity as the tank or close enough not to shock the fish.

Salinity for brackish: 1.005-1.010
 
#4 ·
One would think so but I have killed swords in a tank I added salt to and it didn't take out the feeder guppies.

All I know is I won't add salt on a regular basis again unless I have one, a teaspoon or tablesspoon just doesn't cut it.

I don't remember where I saw it but someone added salt with a tablespoon on a regular basis. It worked for like 4 months but one day they added the salt to the buckets and then added during a water change the water and killed a tank full of mollies. Come to find out the salinity in the tank had almost gotten to levels you see in salt tanks and the added water was a lot lower. It was a mollie tank so no other species in that one.

Just so we get this right, are you talking about reef salt or are you using fresh water aquarium salt that is actually used to treat prasites and is not recommened for brackish tanks? I don't know why but have not heard many that recomend it.
 
#6 ·
When I add salt to my livebearer tank it is at the rate of 2Tablespoons per 5g of water. So, in a 40g tank, if starting from ground zero, add 8 Tbsp. of salt. It should be Salt for reef tanks and not aquarium salt. Aquarium salt is for medicinal use and adds many micro elements to the water and raises salinity only slightly. I actually raises hardness more. I do not use reef salt. Ad the tanks are NOT brackish. And if you are wanting to go brackish, as suggested, I would get a hygrometer or a salinity difractometer.

Now, looking at the mix of fish in the tank, one cannot have a brackish tank with fish such as paradise fish and tetras. This fish will not tolerate such conditions. So, a family tank of livebearers would be best wit hnone of the other fish in their tank.


Temp may also be high for the livebearers. I keep mine around 72-74 degrees. I word of caution here. At such low temps, the possibility of ich increases. Keep an eye out for any outbreak.

So I guess that my suggestion is to keep the livebearers in a tank of their own. Get the equipment suggested. Another thing that I might do is a 50% water change 2-3 times over the next 7-10 days. I would then measure the tanks salinity and add sea salt accordingly as I did my regular water changes. Increase the salinity gradually.
 
#11 ·
Hmm.. I've never had any success in keeping mollies - I believe my water is too soft. I would stick with the fish you have as you're pretty well stocked at the moment with the angels in there, and just continue with the water changes and keep a very close eye on things :)
 
#13 ·
I am here to comment because Stephen emailed me about this thread, sorry it took me so long to get here but I have been out of town for a couple of days.

First thing I want to say is that I disagree with a lot of what has been said here. 1 tbsp of salt for each 10 gallons of water isn't even going to register on a hydrometer. Many molly species, such as the silver mollys can handle full saltwater conditions, with spg/salinity of 1.023 - 1.025.
I have heard no evidence here that the salt caused any of the problems in this tank.

If salt/salinity were the problem, the first fish to be affected by it would be the angelfish and paradise fish who are very sensitive to salt.

I did catch that there was a period of cloudy water. That tells me that there were some fluctuations in the water params, and that does not include salinity. Adding 6 new fish to a 40 gallon tank that is already fully stocked will affect ammonia levels, which I noticed were not listed. Once ammonia breaks down, that means a spike in nitrite. Quite often when the cloudy water hits, it's during a nitrite spike.

There could be any of a number of things that caused the deaths of the mollys, but considering it was just the mollys that died and nothing else has been affected, I would have to think that there was something specific with the mollys that killed them all. It could have been a bacterial infection, fungal infection (early stages don't always show symptoms) the stress of movng them or even a change in their water params from store tank to home tank. With the information that was given, there is no way to say for sure what it was that caused the deaths, but I can say with confidence that I really don't see anything to indicate the salt caused this.

It would be a good idea to keep an eye on the other fish at this point. Not knowing for sure what the problem was means that it could be something that was contageous, especially to other livebearers.

I have been raising mollys for many years. The conditions have varried from saltwater to brackish water to freshwater. Temps have ranged from 75 - 82, and conditions have been very soft to very hard... but never have I had any problems with any of those situations. Mollys are huge carriers of fungal and bacterial diseases, and that is the #1 problem found with them, overall. They are susceptible to a lot of things because there is a large amount of inbreeding happening due to their breeding habits. Inbreeding weakens the immune system, which then makes them more prone to illnesses. I can say that after many years of study and experimentation, I have found that salt only contributes to healthier and stronger mollys. Silver mollys kept/raised/bred in brackish to full saltwater tend to be twice the size of mollys kept/raised/bred in freshwater. Salt content strenghtens their immune systems, and disease/illness problems lessen when conditions are brackish to full salt.

Stephen, you might want to check with the lfs where you purchased those mollys, ask them how much salt if any is in their molly tanks. Going from brackish to freshwater can be quite stressful on them. Your tank, even with the small amount of salt you put in there, would still be viewed as freshwater, and the thriving angelfish and paradise fish would be proof of that. Losing a large amount of salinity would cause problems such as you described, especially if it was all at once.

One last note... feeder guppies are quite tolerant of high salinity levels, fancy guppys and swordtails are not. Feeder guppys can be dropped into full saltwater conditions without acclimation and still survive. Anyone with a saltwater tank using feeder guppys for a food source for carnivore animals can testify to their sturdieness, and that is one thing that makes them so popular as saltwater feeder fish.
 
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