teach

I have had fish for about two years now. Started out with a 10 gallon for my classroom, then my sister gave me a 20 gallon tank for home. Started out with silver mollies, about 4 of them, but they keep having babies, so now I have about 15 adult mollies. A few days ago, about 10 fry appeared. I have not been doing anything with the fry, and most seem to survive ok. My question is: how many mollies can I possibly fit in a 20 gallon tank? In the fall, I plan to take the 10 gallon tank back to my classroom with some of the mollies. How many should I take out, and how do I tell which are females? It would be neat for the kids to see baby fish in their tank...

Also, on a sad note, as I write this, one of my older mollies is dying on the bottom of the tank. Lying on its side, gasping, and has gone a weird sort of brownish color. I guess I just let it die...

I also have two beautiful red tail platies in my home tank. Will these fish breed at some point? They haven't so far; maybe they are the same sex - fingers crossed.

vin

Mollies can get to be anywhere from 4"-6" long depending upon ther variety....In a 20g you'd be able to keep 2 depending upon what they are.....By themselves. They really need more like a 30g....As far as the platies go, they can get as large as 2.5".....If they haven't bred by now, chances are they are of the same sex..

teach

Thanks...my mollies are only about 1 - 2 inches long. I know they will be much better off once I split them all up into two tanks. Does anyone know how to easily tell the sex? Am I looking for a dark spot?

Trpimp147

i would suggest going to a local pet store and asking them to show you on some in there tanks. thats the easyest way i did it but im still fairly new to sexing fish.

poppet

The anal fin of a male livebearer sort of looks like a scrunched up fin, that is his penis. The female livebearer has a fin like a fan at the same spot. Once you see the difference it is very easy to sex them. Sorry about your older mollie.

COBettaCouple

you can overstock a tank if you do more frequent water changes and cleaning, plus treat the tap water with Prime.. but they'll need more room in time as they are major poopers. Ideally, 1" per gallon is what you shoot for, but you can go over for a while if you increase maint. to keep the tank real clean.

http://www.fishlore.com/Forum/index.php?topic=2834.0 - this is a good visual reference to sexing livebearers.

what meds & all do you have? there might be something there to ease her passing for that molly.

if those red-tail platies are male & female, they'll for sure breed.. if you can, you might want to have 3 of them and keep to the general rule of 1 male to 2 females with livebearers (unless you have them all male or female).

teach

Well, the mollie died yesterday - sad, but she was one of the oldest. As for maintenance, I do a 25% change evey two weeks, or more if needed, and I do a complete water change and cleaning every two months. I am fairly new to the world of fish, but seem to do alright. I have learned never to get fish from a store like Walmart, but only from a reputable pet store. I have also learned not to feed them too much, as it just sits around in the tank. All of the other mollies and the platies are very healthy. I had a problem with ich, but treated it right away and was successful. I think that came from the one fish I did get at Walmart.
Thanks for all the advice - I will try to sex my fish.

cress10

Hi teach, from my understanding, it is not necessary to do a complete water change to your tank if you do frequeant small water changes. This may cause your tank to go through the cycleing process again. Take a look at the cycling portion of this site. It helped me out a lot. It could be a reason why your fish has recently died, but it may not be. Good luck with the fish!

Carlos

COBettaCouple

everyone has their routine for cleaning.. i do a 25% water change weekly on our tanks (2x weekly on the overstocked platy tank) along with a cleaning of the substrata. the filter bag gets changed or cleaned every 4 weeks and we use the marineland carbon with regular changes on it.

if you put your filter sponge and substrata into clean treated tap water, a complete water change should be ok but generally regular partial changes should keep things stable.

we're sorry that you lost your molly, but it sounds like it's for the best.

susitna-flower

If your older mollies are healthy, you could consider taking several of them to your LFS and see if they would buy them, or trade them for something you need. This would releave some of the overcrowding. The cleaning you mentioned, sounds like it could have the potential to create a mini cycle, if you kill too many of the bacteria. Water changes and weekly vacuuming of the gravel is much better. Weelky swishing of filter media in discarded tank water is also good. NEVER change the filter media 100% at the same time, always leave some of it to restart the bacteria cultures. The weekly vacuuming will keep you from needing more agressive cleaning.

I agree with FLBattaCouple, you can overstock for a short while, but IF you do this, I would be sure to check every couple of days with an API Mastertest kit, what your water parameters are. You are probably extremely high on the nitrate levels even with your water change schedule. The levels to shoot for are 0 ammonia, 0 nitrite, and 5-10 nitrate. The ph is very forgiving especially in the kind of fish you are keeping.

When my tank was overcrowded, I did a 50% water change every day or every other day. The level I tried to shoot for was under 20. With normal stocking I try to keep it between 5 and 10, lots less stress on the fish. With an overcrowded tank it is very difficult to keep the nitrates down that low. They say fish CAN stay healthy under 40, but my experience is that between 20 and 40 you start having disease problems, and over you will for sure.

The best thing you can do for your kids in the classroom with your tank is to teach them a little science, the nitrogen cycle! Also set a good example, help them understand about keeping an aquarium. The information available here under the beginners guide is a really good place to start.

By the way.....WELCOME TO FISHLORE....


Fish in the Frozen North

0morrokh

With that many fish I would be doing at least a 50% water change weekly or twice a week. Do you have test kits for ammonia, nitrite, and nitrate? With an overstocked tank, it is especially important to be testing your water frequently.

100% water changes are fine once or twice a year, but generally aren't done on a regular basis because it can be a bit stressful for the fish...the main problem however is that you may end up killing your good bacteria, depending on how thorough of a "cleaning" you are doing. You don't want to be washing out your gravel or filter, because this kills good bacteria which stops your biological filtration.

susitna-flower

Vin, what I have read about Mollies, they can get 2-4" , not 4-6"    this would make a tremendous difference in stocking, and we should be as accurate as possible.    This would mean in a 20 gallon tank up to 10 adult mollies, less if they are larger.

Fish in the Frozen North  

                                   

teach

Yes, I have test kits, and all levels are good. The pH is sometimes high, but this does not affect mollies too much, and I use the kit to lower it. Other than the molly that died, all others look healthy and happy. I will take the advice, and not do full cleaning as often. When I have babies in the tank, I am careful not to do too much vaccuming, as I am worried about sucking them up. For some reason, they seem to think this is play time - some have been sucked into the tube on occasion, but come out the other end no worse for wear!

I would take some of the older mollies to the local fish store, if we had one. I live in a small city (about 16,000) and the closest FS is an hour away. I'm sure splitting them up into two tanks will be better, and the kids will love them

susitna-flower

I live almost 2 hours away from my LFS, and transport fish back and forth all the time. As long as you have them in a fish friendly container, with plenty of air room at the top, they should make it just fine. But you should check with them ahead of time to find out if this would be possible.

What I am concerned with is that you said you have more fry, they will need room to grow, as your current situation is overcrowded already.

You have me confused, how do you use your test kit to lower the ph?

What are the readings for ammonia, nitrite and nitrate? Just wondering, it might feel like we are being critical, which isn't our intent at all, just want to help you have a successful happy tank.

By the way, when I am using my vacuum in a tank with fry, I have a mesh bag I tie over the end of the uptake, which still allows water to pass through, but not the fry. It doesn't do anything for the gravel, but usually by the time the fry are a month or two old, they are ok and don't get sucked up.

We always enjoy new participants in the forum, this is a great way to meet interesting folks from all over the world, and enjoy our fish tanks together. Some wild and crazy folks here, check out timg's tanks! He just completed a tea pot town! It started with the idea of a dam breaking and flooding a town and what it would look like! Very imaginative.

Fish in the Frozen North

0morrokh

I am guessing pH adjuster chemicals came with the test kits.


Do you use test strips or liquid test kits? The liquid tests are much more accurate, just fyi.
Also, there is no reason you would need to lower your pH. Just about any commonly kept fish can adapt to any pH. But actually, Mollies come from and probably prefer a pH on the higher side. They wouldn't mind a lower pH, but there is no reason to purposely lower your ph. The problem with using chemicals to change pH is that they tend to always make it fluctuate, which is extremely stressful for fish. They are much better off with a stable pH...the exact reading is not that important. Many people keep their fish (including me) with tap water that is over 8.

COBettaCouple

yea, i'll 2nd 0morrokh's post .. If your pH is altered by more than .2 by the stuff you add remember that fish are happier with stable pH than perfect pH. 7.0 is nice but if you're always moving it up & down to get to 7.0 you'd be better off at a stable 7.6 or 6.4, etc.. the sudden pH changes are stressful to fish. we have some ph stuff like that and i would put so much effort into getting perfect pH until i found this site and although we have high pH here, the fish are more healthy since i just have been leaving it alone.. i don't even test for pH anymore.

0morrokh

I don't bother testing my pH anymore either. Right now I am keeping delicate Otos and dwarf Cories in a pH over 8...they are as happy as can be.

COBettaCouple

it's something how fish adapt.