What are the odds I could keep a small pair of jack dempseys in a 40 gallon? I'd more than likely buy them young. I'd love to have a breeding pair. From what I understand 40 gallons are what they breed jack dempseys in. Any way you can tell what gender they are?

Are they capable of thriving in 8.3 water? And how quickly do they grow? They would be approximately 2" when I get them.

The 40g should be more than enough for a small pair. You will have to get a couple of them and let them figure it out.
Dempsey's pick their own mate and no matter how well you choose your pair, they have the last say of who breeds with who.
What I recomend is put in a couple like 4-6 dempsey's and let them sorted out. Remember to scoop out the non contender though , they will be hanging out by the water surface or underneath the filter.

For PH I would recomend 6.5-7.2

Sexual Differences:

Its kind of hard sexing dempsey's when their young but here are some things to look for. The male has a longer and more pointed dorsal fin than the female. The male may also have a round black spot in the center of the body and at the base of the tail. The female has fewer spots than the male.

When you say "40 gallon" I assume you mean a "40 breeder" (36x18x16)? If so then yes it can be done. But when the pair maxes out they are going to need a 50 breeder or standard 55. I find it best to always plan for the adult size when buying fish.

JDs prefer neutral to slightly alkaline water with a temperature of 75º to 80ºF. 8.3 is gonna be way high for these guys.

Sexing them is not too tough when they reach a decent size as males have a longer and pointed dorsal and anal fin, while the female does not. It can be tough when they are little. The best way is to get several (5 or 6) and just let them pair off but you need a bigger tank for that method.

Heres an excerpt from an article on breeding...

If a pair has formed in you tank they will fiercely defend a territory of the tank and make the rest of the occupants miserable. It would be best to put up a tank divider giving the supposed pair 1/3 of the tank and 2/3 to the rest of the fish. Once this pair has actually spawned, move them into their own tank, a 45 gallon are larger will be sufficient. Their first spawn is a guaranteed sign that they are a pair. You can choose to keep this spawn or not. If you do, the parents will take care of the fry until they get more and more independent. You can then remove the fry and place them into a 30 gallon and raise them from there, giving them a bigger tank when they need it.

When you set up the breeding tank, use 2/3 tank water and 1/3 dechlorinated tap water. There should be gravel to keep rocks in place. JDs will spawn in clay flower pots. Place the pot on its side and don’t face the opening to the front of the tank, the pair will feel threatened. The filter should be appropriate for the tank size. Put sponge or foam around the filter intake to prevent the fry from being sucked up when they hatch. (You should put the foam or sponge in the tank before you put the pair into it.)

The pair will clean the inside of the flower pot or a flat piece of slate laying on the bottom of the tank to prepare the spawning site. When the pair are ready to spawn, the female will lay her eggs on the spawning material as the male fertilizes them.

The eggs should hatch within 48-56 hours, depending on the temperature. Temperature in the breeding tank should be 76º to 82ºF. When the eggs hatch, the parents will take care of them. When they reach a size of 1/2 inch, they should be very independent and should be removed and placed into a raising tank of 20 gallons. If the tank is too big, the fry will have a hard time finding food. When the fry are free swimming you can feed them newly hatched brine shrimp. When you remove them they should be fed a variety of foods. Flakes and adult brine are commonly used. A sponge filter in the fry tank will be sufficient filtration and won’t suck up fry.

If you have any other questions please don't hesitate to ask...

AAO

Sorry CC! I see we crossed posts! LOL!

Its all good at least we are working

Good informative replies! Certainly answered all of my questions.

I won't have an RO filter for a few more months, so in the meantime, are there any good cichlids that can fit in a 40 breeder that can survive in 8.3 water?

I'd prefer a pair and some dither fish of some kind. I liked the JD's because of the fact they would eat crawfish. I thought that was pretty cool for some reason.

You could always get some africans but you should also try some PH DOWN or if you could get it, MURIATIC ACID I have used it use it to drop ph. Just drops of this acid will give you quick results.

You know I thought about purchasing some Nuetral Regulator, but I hate to adjust the water with chemicals. I'm curious as to how that stuff works though and how often it needs to be put in the tank to keep 7.0. I hate to spend so much money on the powders and liquids. I'm hoping to have an RO filter in a few months.

I remember that i use to pay $ 4.00 for a galon of acid and that would last you an eternity since you only put in some drops at a time to lower ph. as for raisng it baking soda is about the cheapest thing you could buy.

With the acid though, is the water stable? Or does the pH fluctuate wildly and chaoticly?

depending on the gallons of your tank and how much water you change. It does take a bit to master the amount you put in it but if you are consistant you shouldn't have a problem.

How often do you have to add the acid to keep the pH stable in say, 40 gallons of water?

Where do you get the m. acid?

You have PH of 8.4 why would you want to lower the ph? Anyway a couple of drops would do. You have to experiment to get the correct amount. I'm actually sure that is drops though. You can find this stuff in a pool supply store or home depot. Another thing you have to dilute this with water before you put it in the tank.

Remember this stuff is really dangerous and proper precaution should be taken when using acid. Use the 33% kind which is the least strongest. I started using this stuff when I was working as a pool operator and it worked wonders.

Can dempseys survive in 8.4 though? I was actually thinking of trying a pair of electric blue dempseys. What do you think? Maybe a tankmate or two. I'd move them to a 55 or 75 for sure within a year or so.

I was going to try and lower it in some of my smaller tanks, like the 29 or 10 gallon so I could keep angelfish and tetra fish.

I think 8.4 is a little too high. Try 8.0. You could throw in some Giant Danio in there for tankmates.

If you are going to put blue dempseys in there you better get that ph situation straighten out. Blue dempsey's are expensive , you wouldn't want something to go wrong those fish are expensive.

I'm reading some scary stuff here. PH for the vast majority of CA/SA cichlids is 6.8 to 7.2! PH in the 8's is way too high. And frankly adding the Muriatic acid sounds like more trouble (to regulate) than it's worth. Not to mention being a dangerous chemical to keep around. Use a commercially available neutralizer for safeties sake. Plus Blue Dempseys are very delicate and timid fish. They will not tolerate advers conditions or boisterous tank mates like regular JD's will.

With cichlids a stable PH is much, much more important then a "correct one". You'll find quite a lot will adjust to a PH that is out of their prefered range (actually most do due to centralised filtration systems at LFS's) but as soon as you try adjusting PH chemically you run a massive risk of swings and an unstable PH which will do a lot more damage then a PH that is out of their recommended range. If your particularly looking to keep species that you think wont do well in PH 8+ you can try methods of lowering PH without chemicals (peat moss, driftwood etc.). To be honest though I know a few very successfull CA/SA cichlid keepers with a PH similar to yours.

Is the LFS you buy fish from in the same area as your home? If so maybe ask out of interest, what their standard PH is and if they alter it chemically? They may do as it's a lot easier to keep stable if running of CF, but you may also find their PH is fairly high also.

okay since this is about jack dempseys in a tank okay i read u guys said out 4-6 dempseys when there small i have a 20 gallon and a 30 gallon the 55 gallon i am getting in a couple months so how should put the dempseys in the tank? Would the 55 gallon be fine for 2 dempseys?