Tank Mates For Dalmation Molly?

I have had a 10 gallon tank for 2 years with 2 cory catfish, 2 Dalmatian Mollies, and 2 Platies. One Dalmatian Molly died within 2 weeks of when the tank was started. The other platy lasted for a year with the other platy and the 1 Molly and 2 Corys. So, 1 Dalmatian Molly (Short Tail - male) and 1 Mickey Mouse Platy (male) and 2 Cory Catfish lived together in happy harmony for 1 more year (for a total of 2 years) without any trouble. It is my young son's tank so he asked if he could get a friend for each fish again. So we did. We added a Sunburst Platy and a Dalmatian Molly. Things went crazy for 2 days and then calmed down. Then 6 days into the new tank mates, the Sunburst Platy appeared to be pecked to death. Then, the 2 year old Platy looked stressed the next two days and dies. Then within a week our 2 year old black Dalmatian Molly dies. The Corys are fine and I am doing my regular water changes and changing the filter. I have concluded that the remaining Dalmatian Molly is very aggressive. He was chasing and pecking everyone. We have been given a 20 gallon tall tank as I am hoping more room will help him be calmer. I will be preparing this tank for him for a week or so. My question is: what can I put with him that he will not bother? He seems to be fine with the 2 Cory Catfish I have, but can I safely get any other fish? My other Dalmatian Molly was fine in a 10 gallon for 2 years with a platy or 2, but this current Molly doesn't seem as friendly.

One more thing: I don't wish to breed live bears either. So, I didn't want to buy 3 females for my male Dalmatian Molly.

 

HI there, welcome to fishlore.

What are your tank water's parameters? (ammonia, nitrite, nitrate)

Do you know about the Nitrogen Cycle? You aren't really suppose to change the filters, because the filter is what has all of the good bacteria that maintains your cycle. When you change the filter your cycle restarts. That can be pretty stressful for fish. The other thing is your ten gallon was overstocked which probably contributed to the stress and weakened immune systems of your fish.

Both mollys and cory catfish should not be in a ten gallon. Mollys have a large bioload so do best in a 29 gallon or larger. Cory cats are very active and do best in groups of 6 or more, so a twenty gallon long or bigger is recommended.

I would suggest you rehome your Molly and cory cats or get a larger tank that can hold both. If you get a larger tank you can then add at least four more cory cats of the same species type. As it is I would not add more fish to your tank since it is overstocked.

 

Actually, the two cory catfish are only one inch, maybe 1 1/2 inches long. I have two and they have lived happily together without any stress or disease for two years. I had one Dalmatian Molly and 1 Mickey Mouse Platy also for 2 years and everything was fine until I added the two new fish two weeks ago. These 4 fish were all in a 10 gallon tank together for two years. Maybe I will just keep the Molly alone with the 2 cory catfish and just see how long he lasts as it doesn't seem that he is a good fit for the 20 gallon either. I really had great success with the first Molly we had in the tank for 10 years. He was a great fish! I am sorry we tried adding a "friend".

HI there, welcome to fishlore.

What are your tank water's parameters? (ammonia, nitrite, nitrate)

Do you know about the Nitrogen Cycle? You aren't really suppose to change the filters, because the filter is what has all of the good bacteria that maintains your cycle. When you change the filter your cycle restarts. That can be pretty stressful for fish. The other thing is your ten gallon was overstocked which probably contributed to the stress and weakened immune systems of your fish.

Both mollys and cory catfish should not be in a ten gallon. Mollys have a large bioload so do best in a 29 gallon or larger. Cory cats are very active and do best in groups of 6 or more, so a twenty gallon long or bigger is recommended.

I would suggest you rehome your Molly and cory cats or get a larger tank that can hold both. If you get a larger tank you can then add at least four more cory cats of the same species type. As it is I would not add more fish to your tank since it is overstocked.

I am sure the water parameters are not great now that I have had 3 fish die, but previously they have been fine. The tank has had the same fish for 2 years with weekly (and sometimes every 2 weeks if I was lazy) 10% water changes. Every two months I change the Bio-Bag disposable cartridge in the filter. My kit says to change it monthly, but I usually don't. It has been 2 months since I have changed it. Nothing was changed before I put in the two new fish. I use Tetra AquaSafe and Tetra Easy Balance when I make the weekly 10% water changes. I also monthly or every 2 months I use Tetra SafeStart that puts in healthy filter bacteria (I do this after I change the disposable Filter cartridge Bio-Bag thing). I also use API stress coat later in the day after a water change or change of the disposable Filter cartridge Bio-Bag. It has worked good for 2 years in this 10 gallon tank and I haven't even had any diseases I read about on here. I did none of these changes before adding the 2 new fish. SO... I guess the additional Molly overloaded the tank and caused the stress. Which in turn caused, three fish to die (my 2 fish who were 2 years old and the additional new Platy). But I did not set up a QT tank before adding those new fish. That might have helped. I just introduced the new fish after making small water changes to their bag from Ptsmart for over an hour while the bag hung out in the aquarium. So... I guess also that I had an unusual Molly who hung out with a Platy and 2 corys for 2 years without pecking them or having any sign of disease?

 

Maybe it is the kind of Molly too. What do you think? I had a nice one in the 10 gallon for 2 years that was basically black with a short fin, but they called him a Dalmatian Molly at the store. I got another Dalmatian Molly (the new one I introduced that is still living and caused all the havoc) and he is silver with black spots, but has the sailfish tail. Maybe I should also stick to those black one with the short fins. Do you all find that certain kinds of male mollies are more gentle than others? Or is it just personality within that kind?

 

Actually, the two cory catfish are only one inch, maybe 1 1/2 inches long. I have two and they have lived happily together without any stress or disease for two years. I had one Dalmatian Molly and 1 Mickey Mouse Platy also for 2 years and everything was fine until I added the two new fish two weeks ago. These 4 fish were all in a 10 gallon tank together for two years. Maybe I will just keep the Molly alone with the 2 cory catfish and just see how long he lasts as it doesn't seem that he is a good fit for the 20 gallon either. I really had great success with the first Molly we had in the tank for 10 years. He was a great fish! I am sorry we tried adding a "friend".




I am sure the water parameters are not great now that I have had 3 fish die, but previously they have been fine. The tank has had the same fish for 2 years with weekly (and sometimes every 2 weeks if I was lazy) 10% water changes. Every two months I change the Bio-Bag disposable cartridge in the filter. My kit says to change it monthly, but I usually don't. It has been 2 months since I have changed it. Nothing was changed before I put in the two new fish. I use Tetra AquaSafe and Tetra Easy Balance when I make the weekly 10% water changes. I also monthly or every 2 months I use Tetra SafeStart that puts in healthy filter bacteria (I do this after I change the disposable Filter cartridge Bio-Bag thing). I also use API stress coat later in the day after a water change or change of the disposable Filter cartridge Bio-Bag. It has worked good for 2 years in this 10 gallon tank and I haven't even had any diseases I read about on here. I did none of these changes before adding the 2 new fish. SO... I guess the additional Molly overloaded the tank and caused the stress. Which in turn caused, three fish to die (my 2 fish who were 2 years old and the additional new Platy). But I did not set up a QT tank before adding those new fish. That might have helped. I just introduced the new fish after making small water changes to their bag from Ptsmart for over an hour while the bag hung out in the aquarium. So... I guess also that I had an unusual Molly who hung out with a Platy and 2 corys for 2 years without pecking them or having any sign of disease?

Inches mean nothing when it comes to what fish go into what tank size. Cory cats are very active fish as I'm sure you have seen. They also like bigger groups, that is why ten gallons is too small for them. They obviously have had some stress since they became sick and started dying on you. I agree that not doing a quarantine for new fish probably didn't help either.

Maybe it is the kind of Molly too. What do you think? I had a nice one in the 10 gallon for 2 years that was basically black with a short fin, but they called him a Dalmatian Molly at the store. I got another Dalmatian Molly (the new one I introduced that is still living and caused all the havoc) and he is silver with black spots, but has the sailfish tail. Maybe I should also stick to those black one with the short fins. Do you all find that certain kinds of male mollies are more gentle than others? Or is it just personality within that kind?

Probably has nothing to do with the kind of Molly. Each fish has it's own personality, even among those who school. As I said earlier I would not add any other fish into your ten gallon since it's already overstocked, and ten gallons is too small for a Molly.

 

Inches mean nothing when it comes to what fish go into what tank size. Cory cats are very active fish as I'm sure you have seen. They also like bigger groups, that is why ten gallons is too small for them. They obviously have had some stress since they became sick and started dying on you. I agree that not doing a quarantine for new fish probably didn't help either.




Probably has nothing to do with the kind of Molly. Each fish has it's own personality, even among those who school. As I said earlier I would not add any other fish into your ten gallon since it's already overstocked, and ten gallons is too small for a Molly.

Fortunately, my 2 Cory Cats are doing fine. They are not sick and are playing together just like normal. They actually are the ones that were never bothered by the Molly and still are not being bothered by him. They have been doing well in that 10 gallon tank for 2 years so I just won't disturb them. I have discovered that when you have a good tank going for 2 years (4 fish in a 10 gallon) that you should just let it be and not add new fish. It is my 9 year olds fish tank and he wanted to get new friends for them so I caved. Of course, now he is sad over losing his favorites and is mad at the new Molly. But, in time I am sure he will grow to like the new Molly who currently seems to be doing fine. I did my water change and checked the water and every thing is good. The additions were just too much stress I am guessing.