Please Help Me Identify This Murderous Fish...

[bizkitt]

Long story short...
My son has a 20 gallon tank. We got a few dalmation mollies and about 10 fancy guppies from a friend. A small fry was located in the tank months later..it hatched? This fish looked like nothing that was in the tank, grew bigger and bigger and ended up killing everything in the tank but one lone surviving guppy. (she's one here way out with torn fins) Can you identify this fish?

Very aggressive, kind of golden color under bright light, under aqaurium light shows a very beautiful blue shimmer.
Pretty flowing top fin ..

He seems to be getting BIGGER..so no more fish for us. Meanie!

Question..what is it?
Is it possible to have a "rogue" fish just show up from unknown hidden eggs?
Am I nuts? hehe...

Please excuse my photos. Fish are hard to photograph!
Thanks in advance!

 

[Davo86]

Hi
Firstly your fish are livebearers so there would be no eggs,
The fish in question looks to be a male sailfin molly, it is possible that one of your dalmation previously had bred with a sailfin and this was the result,
As you have found out the males can be quite boistrous and can get to 6"

 

[Jodiem]

it looks like a cross between the mollies and the guppys, these are both livebearers so no eggs would have been layed. You may be able to sell it to a fish shop or advertise it in the paper or something if you want to get rid of it but it is a very nice colour!
Hope this helps

 

[Tokis-Phoenix]

Its a male molly- you say you got some female mollys as well as guppys? Then this male is the result of your female mollys- like a lot of other livebearers, mollys can store sperm in them, meaning that they can have numerous pregnancies resulting from a single mating even if there is no male currently present.

Also are you absolutely positive that its the molly that was killing off the guppies- did you actually see it in the act of being aggressive towards the guppies and other mollys?
Its more likely that disease or water quality problems killed the others off, male mollys are not killers/very aggressive fish by nature. You say the last remaining guppy has torn fins? Thats a symptom of numerous diseases, which can be lethal left un-treated.

 

[bizkitt]

Its a male molly- you say you got some female mollys as well as guppys? Then this male is the result of your female mollys- like a lot of other livebearers, mollys can store sperm in them, meaning that they can have numerous pregnancies resulting from a single mating even if there is no male currently present.

Also are you absolutely positive that its the molly that was killing off the guppies- did you actually see it in the act of being aggressive towards the guppies and other mollys?
Its more likely that disease or water quality problems killed the others off, male mollys are not killers/very aggressive fish by nature. You say the last remaining guppy has torn fins? Thats a symptom of numerous diseases, which can be lethal left un-treated.

I see him physically attacking the last remaining guppy. She was fine and then he tore her tail fin almost off. He killed the two dalmation mollies we had and about nine guppies. I didn't realize he was the culprit until recently. He attacks constantly.

Sorry about the egg thing. As you can tell I am a novice when it comes to tropical fish breeding.

Thanks everyone for your help!

 

[Tokis-Phoenix]

I see him physically attacking the last remaining guppy. She was fine and then he tore her tail fin almost off. He killed the two dalmation mollies we had and about nine guppies. I didn't realize he was the culprit until recently. He attacks constantly.

Sorry about the egg thing. As you can tell I am a novice when it comes to tropical fish breeding.

Thanks everyone for your help!

Thats quite unusually very aggressive behavior for a male molly considering the tank is a fine size for him and he had females- but i guess fish do have individual personalities, perhaps this is just a particularly nasty male molly. It might just be better to rehome him them, see if any pet shops can take him off you- it may also be good to get a medicine called Melafix for the remaining guppy, as it is very good at helping prevent secondary infections setting into wounds on fish and it generally aids the healing process .

 

[bizkitt]

I see him physically attacking the last remaining guppy. She was fine and then he tore her tail fin almost off. He killed the two dalmation mollies we had and about nine guppies. I didn't realize he was the culprit until recently. He attacks constantly.

Sorry about the egg thing. As you can tell I am a novice when it comes to tropical fish breeding.

Thanks everyone for your help!

Thats quite unusually very aggressive behavior for a male molly considering the tank is a fine size for him and he had females- but i guess fish do have individual personalities, perhaps this is just a particularly nasty male molly. It might just be better to rehome him them, see if any pet shops can take him off you- it may also be good to get a medicine called Melafix for the remaining guppy, as it is very good at helping prevent secondary infections setting into wounds on fish and it generally aids the healing process .

I will look into the medicine. I looked at a few pics of sailfin mollys. Sure looks like him.
What a bully!!
Thanks for helping me!

 

[Tokis-Phoenix]

I will look into the medicine. I looked at a few pics of sailfin mollys. Sure looks like him.
What a bully!!
Thanks for helping me!

I'm glad to help .

 

[Butch]

Actually, this aggressive behavior is common in sailfin mollies and its hybrids, they always picked on other fishes, even on each other. I have three mollies in 20gal with endler hybrids and the mollies always picked on the females endlers and the huge male endlers.

Maybe you could add three or four more female mollies so he can probably will become less aggressive?

Plus I really like your sailfin, don't give him away because I never seen that molly before, especially in stores.

 

[abzorbd]

I have one that's about three inches long and all he does all day long is try to mate with the females. He's aggressive about it but only to the point where he doesn't give up. He's never actually tried to attack any of my fish. I have him with guppies, rasboras, more mollies and such.
When he tries to mate his sail stands up on end and it looks beautiful.

Please ignore the flakes. It was feeding time.

 

[bizkitt]

I have one that's about three inches long and all he does all day long is try to mate with the females. He's aggressive about it but only to the point where he doesn't give up. He's never actually tried to attack any of my fish. I have him with guppies, rasboras, more mollies and such.


Wow your fish looks just like mine. Nice!

 

[Davo86]

How many other mollys did you say you had and do you know how many of them were female?
The sailfins do get quite frustrated when there aren't enough females around

If you were to add say 5 good sized female mollys it should calm him down,

 

[tropicaltink81]

How many other mollys did you say you had and do you know how many of them were female?
The sailfins do get quite frustrated when there aren't enough females around

If you were to add say 5 good sized female mollys it should calm him down,

hi id say molly guppy cross , looks a nice fish nice colour, they have just inter bred,

i have a platy had her years and she is my best breeder she has up to 50+ fry a month shes been fantastic
untillher batch of fry 2 month ago she has been geting it away with one of my swords iv just discoverd as one of her fry has developed a sword,the little bugger, fish are like humans when they get a itch they will scratch it like ne man lol soz guys,

ur not alone,

 

[Davo86]

The fish in question is not a cross at all but a sailfin molly (either Poecilia latipinna or Poecilia velifera)