Another odd question

Question
Hey Chris, sorry to bother you again. I'm listed as an expert here, and yet, I find the more help I offer people, the more interest (and questions!) I find in my own water world!

Before I dig into my questions, my Hillstream loaches are a gorgeous addition! Between you and Nicole on this site, I found out just about everything I needed to convince myself to make a purchase. Two, in fact! Thanks again.

Now, for the question at hand. I've been spending particular interest in breeding and, more specifically, trying to enlarge and brighten guppies to make them more suitable for a barb tank. Large enough that a fin nipper wouldn't feel as apt to pick on it. Up to this point, I never really took note on how to sex my fry until they were large enough (and colorful enough) to know which to keep for the parent tank, and which to give away. Now that I'm seeking to find a deeper understanding of the whole process, I'd like to know: How do you sex fry? When are the first signs easily observed? Is there a specific way to get a female / male dominant drop? And what little in's and out's to breeding are not-so-commonly known, but but essential to quality as well as quantity breeding?

Next on my agenda is something a bit more mechanical. Do you know the thickness of glass / acrylic needed per gallon? Or possibly a reliable place to find such information? I tried a scale test of formulas from several different sites and most had catastrophic failures. Disappointed, and somewhat shocked that these sites have yet to be red-flagged as false, I'm just wondering if there are any trusted sites, or if i need to call up my old physics teacher for some stress over time equations... Along with that, for sealant, will a silicon based caulking cause problems for fish? RTV, perhaps? I've used RTV before for patching tanks, but it was always temporary and i replaced the whole tank within a few weeks. I'm just concerned over the long term effects. (My secret goal is to build my own 100+ gallon tank. Curved for 180 degree viewing.) If you know yourself, or know somewhere i should look into, that'd be great. If not, I'll let ya know what i find!

Thanks again, and sorry for the completely random questions!

Answer
Hi Darryl;

I'm glad the hillstreams are working out. They are a nice looking little fish.

I don't think guppies could ever be big enough to avoid being picked at by barbs. Fish that tend to nip fins just love those nice flowing tails. It isn't the victim's size as much as it is what they have to pick at.

To sex guppies and other livebearers you have to wait until the males are old enough to show their external sex organs. Once the anal fin starts to get pointy you will know the males. They are usually at least 3 months old by then. I don't personally know of any methods to encourage more of either sex. It is important with all livebearers to keep up with regular water changes. Normal maintenance for all tanks of any fish is replacement of 25% of the water once a week. Vacuum the gravel every 2 weeks. Professional breeders change the water in their baby grow-out tanks daily to encourage fast growth. Yep, that's what I said...every day! Feed the youngsters 4 or 5 times a day, but very small amounts. Siphon out leftovers right away. It's good to have tanks with no gravel for babies just for that reason. It's easier to clean and food and waste won't get stuck where you can't remove it promptly.

I've never built a tank so I really can't help with the thicknesses of the material used. You could look at the specs of commercially made ones for that and go from there. There are many different companies out there and they all have lists and charts of what they make along with the sizes, dimensions and thickness of the glass or plexiglass.

Always use 100% silicone sealant that is non-toxic when cured. Anything else is a risk. I don't know what RTV is but I would check the label to if it's safe for aquariums.

Let me know what you come up with!

At Your Service;
Chris Robbins