Could the lack of a heater have stunted growth?

HI everyone.
This is a question that has been bothering me for a long time, so I thought why not get some worthy opinions from everyone here?...
Ive had a swordtail pair in my 12 gallon since last may, the male died but however the female gave birth to you ones, out of which only 2 have survived :/... These babies were born on July 25th. Because I couldn't find one, the babies have been living in the tank with their mother withor a heater so far. Anyways I got one yesterday... But I'm very worried of their size, Theyre only about 1-1,3 inch and isn't that TINY for six month old swordtails? Could the cold water have caused this? The tank has always been in my living room, so its temp must've been around 10-15 degC without heating...
Anyways do you have any answer for this? Now that the heater is keeping the water at 24 deg C, I don't want them to have ' traces ' of late growth, you know what I mean ( problems that might develop later )...
Will appreciate any opinion.
Thanks!

 

I don't think it's related to cold water though I would get a heater. I could be fungus related?not completely sure though.

 

I don't think it's related to cold water though I would get a heater. I could be fungus related?not completely sure though.

Yeah I bought one yesterday as I said above... The fish are doin well, but I think it's the water since swordtails are tropical fish...

 

Glad you got the heater. It will be interesting to see if living in a more appropriate temp stimulates their growth. ;D

 

Interesting question.
Would cooler water slow metabolism and warmer water speed it up?

 

Frequent large water changes help to dilute growth hormones that become present in the water and help to encourage growth. If too much of this hormone is present in the water, it slows down their growth and can stunt fry and juveniles. I don't know if this affects swordtails the same as it can for other types of fish but I thought I'd throw it at you as a possibility that you can consider or rule out, depending on your own aquarium maintenance routine.

 

Interesting question.
Would cooler water slow metabolism and warmer water speed it up?

Yes, that's how it works. Large mouth bass are a good example. Fish down south reach their maximum size in just a few years, while fish up north don't reach their maximum size until they are several years older. There isn't much of a difference between the maximum sizes, though.....it's just a matter of surviving long enough to get that big, which southern fish have the advantage on.

Not sure if that's how it works for swortails too, but there is a physiological reason for it which I think is likely to be found in other fish. However, it might be that keeping the fish in 55 F water has done them damage.

 

Yeah now I'll wait and see what will happen... I thought that warmer water would speed up their metabolism, since it does so with the blue crayfish and the goldfish...
I really hope it didn't damage the young ones ... I hope there's something I can do, I'll wait and let everyone know...

 

I've also heard that captive fish tend to grow slower since it is in a enclosed envioroment so it seems more crowded.