Over Stocked?

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Ok awesome! Yea I'm mainly worried about the oscars when everyone gets bigger but my girlfriend really likes the oscars and the tank is in our living room. I do weekly water changes at around 30% currently With an occasional 50%. I do also like the idea of some corys and tetras though! haha dang this is gonna be a hard decision! I also thought about (if it were only severums) adding in some german blue rams. Do you think that would work, or do you think the severums would eventually eat them? I really appreciate all of the good ideas and feedback so quickly!!
That's perfect with the WC schedule - keep that up and you'll be golden.

Corys and tetras will get taken down by the Oscars pretty quickly. Corys and severums is a little risky, I'd be worried about a big severum accidentally getting a Cory in it's mouth, which would likely mean death for both fish.

What kind of tetras were you thinking? Most or all of the bigger species should do fine with severums.

Keep in mind - polys will eat all your tetras and Corys.

I think rams and sevs would be fine.

Drew
 
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Ok awesome! Yea I'm mainly worried about the oscars when everyone gets bigger but my girlfriend really likes the oscars and the tank is in our living room. I do weekly water changes at around 30% currently With an occasional 50%. I do also like the idea of some corys and tetras though! haha dang this is gonna be a hard decision! I also thought about (if it were only severums) adding in some german blue rams. Do you think that would work, or do you think the severums would eventually eat them? I really appreciate all of the good ideas and feedback so quickly!!
I would do 50-60% weekly, and once a month do two 75% water changes, one right after the other so nearly all the water is removed.



Nitrates aren't completely removed unless you remove all the water in the tank and start with fresh water, because assuming you feed your fish the same amount each week, they will produce the same amount of nitrate between each water change.

As an example, if your tank made 20ppm of nitrate weekly, doing a 50% water would dilute the nitrate to 10ppm. The next week, before you do the water change, the nitrate is at 30ppm. This is because it started at 10ppm, and then the fish added another 20ppm. This will always happen unless you change all the water. Larger water changes only delay the rise in nitrate.



The equation for dilution is (C₁ x V₁) = (C₂ x V₂)

C₁ = Concentration before dilution, in this instance nitrate concentration.

V₁ = Volume before dilution, but for water changes you use the amount of water left after the water is removed but before it's refilled (if you had a 100 gallon tank, and you did a 20% water change, then 80 would be plugged into V₁. Whatever % of a water change you do, you make it a 2 digit decimal (20% = 0.20, 64% = 0.64. etc...), subtract it from 1, then plug the difference into V₁. For example, .95 would be used for a 5% water change, .63 would be used for a 37% water change, etc...).

C₂ = Final concentration of nitrate, after the water change is done. This is the variable that's being solved for.

V₂ = Final volume, the amount of water in the tank after the water change.



If you do 30% water changes weekly, and your fish create 20ppm of nitrate each week, then your nitrate would be 14 after the first week, 23.8 after the second week, then 30.66, 35.462, 38.8234, etc... By the time it hits 45 nitrates (just in this instance, not for every tank), it slows down to +0.1ppm per week. Although it may slow down at 45ppm, it is still increasing each week.

(C₁ x V₁) = (C₂ x V₂) --> (20 x 84) = (C₂ x 120) -->
(1680) = (C₂ x 120) --> (1680) = (C₂ x 120) --> (14) = (C₂ x 1) --> 14 = C₂
--------------------------
120

Sorry for the lengthy post, I just think this is something everyone should know.
 
David,

Are you able to get a tank with a larger footprint for the oscars? Perhaps if you're good at DIY projects, you could take down your tank and use the panels to re-build it, making it 48" long, 24" front to back, and 18" high. This would certainly make your oscars much happier. If not - they will probably be OK with the current footprint, but space for tankmates will be limited.

If I were you, I would change the footprint of the 120, and keep the two oscars in there. If you are set on dithers, I'd throw in a half-dozen giant danios and call it a day. Keep up with weekly water changes, and this would be a killer setup.

Then in your 75 - do one of your severums (whichever one you like the best), and whatever polys you're wanting. I'd probably do 3-4 ropefish, along with some lower jaw polys - a pair or trio or sens would be cool, and throwing a delhezi in there wouldn't be too crazy.
You can do just about any upper jaw in that tank, with the exceptions being Weeksii, Teugelsi, and Ornate.

Drew
 
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Then in your 75 - do one of your severums (whichever one you like the best), and whatever polys you're wanting. I'd probably do 3-4 ropefish, along with some lower jaw polys - a pair or trio or sens would be cool, and throwing a delhezi in there wouldn't be too crazy.
You can do just about any upper jaw in that tank, with the exceptions being Weeksii, Teugelsi, and Ornate
Severums and polys would be straight overstock. You do realise that lower jaw species are the largest?

4 polys, 4 ropes and a pair of severum?? I'd go max 3 polys and 4 rops alone. Senegalus, delhezi or palmas complex
 
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That wouldn't work out very well...

Severums and polys would be straight overstock. You do realise that lower jaw species are the largest?

4 polys, 4 ropes and a pair of severum?? I'd go max 3 polys and 4 rops alone. Senegalus, delhezi or palmas complex

Ugh, I do this all the time - I meant upper jaw polys. To be fair I did say upper jaws later on - but to David, upper jaw polys, with the exception of Weeksii, Teugelsi, and Ornate. Lower jaws really need bare minimum of 18" width, and preferably 24"+.

Hendre, I didn't suggest a pair of severums in the 75. That would be far too heavily stocked, even without the polys - I think it's Baltimore that's got some severums in a larger tank (over 1K gallons), they really fill out when you give them the space.
One severum needs 75, and a bigger footprint would always be better.
3-4 polys (my suggestion with this stocking level was 2-3 sens and a del) plus 3-4 ropefish isn't outrageous. There are plenty of tanks with bichirs (UJ and LJ) completely covering the bottom of the tank, that do perfectly fine. Not saying I agree with that stocking level, but just that it clearly works.

If he keeps up with his weekly water change schedule, he should be fine.
 
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I would do 50-60% weekly, and once a month do two 75% water changes, one right after the other so nearly all the water is removed.



Nitrates aren't completely removed unless you remove all the water in the tank and start with fresh water, because assuming you feed your fish the same amount each week, they will produce the same amount of nitrate between each water change.

As an example, if your tank made 20ppm of nitrate weekly, doing a 50% water would dilute the nitrate to 10ppm. The next week, before you do the water change, the nitrate is at 30ppm. This is because it started at 10ppm, and then the fish added another 20ppm. This will always happen unless you change all the water. Larger water changes only delay the rise in nitrate.



The equation for dilution is (C₁ x V₁) = (C₂ x V₂)

C₁ = Concentration before dilution, in this instance nitrate concentration.

V₁ = Volume before dilution, but for water changes you use the amount of water left after the water is removed but before it's refilled (if you had a 100 gallon tank, and you did a 20% water change, then 80 would be plugged into V₁. Whatever % of a water change you do, you make it a 2 digit decimal (20% = 0.20, 64% = 0.64. etc...), subtract it from 1, then plug the difference into V₁. For example, .95 would be used for a 5% water change, .63 would be used for a 37% water change, etc...).

C₂ = Final concentration of nitrate, after the water change is done. This is the variable that's being solved for.

V₂ = Final volume, the amount of water in the tank after the water change.



If you do 30% water changes weekly, and your fish create 20ppm of nitrate each week, then your nitrate would be 14 after the first week, 23.8 after the second week, then 30.66, 35.462, 38.8234, etc... By the time it hits 45 nitrates (just in this instance, not for every tank), it slows down to +0.1ppm per week. Although it may slow down at 45ppm, it is still increasing each week.

(C₁ x V₁) = (C₂ x V₂) --> (20 x 84) = (C₂ x 120) -->
(1680) = (C₂ x 120) --> (1680) = (C₂ x 120) --> (14) = (C₂ x 1) --> 14 = C₂
--------------------------
120

Sorry for the lengthy post, I just think this is something everyone should know.
I just realized that the last equation in this post didn't work properly. This is what it should be:

(C₁ x V₁) = (C₂ x V₂)

(20 x 84) = (C₂ x 120)

(1680) = (C₂ x 120)

(1680) = (C₂ x 120)
-----------------------
120

(14) = (C₂ x 1)

14 = C₂
 
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Ok I had an issue little over a month ago about my Oscars being unnaturally shy. I posted my problem on here and went through all of the suggestions until I came down to the last resort of going with the idea of either adding some dither fish or as someone mentioned adding in another active cichlid. So I added two 3' turquoise severums (because I couldn't decide which one looked cooler) and it totally worked after about a week.The oscars are way friendlier and not just hiding from me when I approach the tank. One of the oscars is even eating out of my hand now. As of right now everyone gets along and has more than enough swimming space (120g 60'Lx24'Hx18'F2B) but, even though the guy who sold me the severums, told me that the tank will be big enough for all of the fish long term I have my doubts. So I am looking for some suggestions, Should I get rid of one of the oscars, or both? Should I get a 75g and just put one oscar in there? Or what do you all think? I kinda like the idea of moving the oscars some where and turning the 120g into a semi aggressive south american cichlid tank with maybe adding in 1 or 2 electric blue acaras. What are your opinions?
Stock list: 2 tiger oscars, 2 turquoise severs, 1 Dino bichir, 1 reed fish (have potential plans of probably moving the two air breathers to an oddball tank in the future.
If you take the oscar in his own tank you could try a shoal of 5 slender hemiodus tetras, they get to 16cm and look pretty interesting
 
I agree with Angelphish, that as they grow a more rigorous water change schedule will be needed with just those cichlids in the tank. I'd do 3 x 30% water changes per week when they are adults.
If you do get corys, they will need to be large enough not to temp the oscars into trying to swallow them.
Corys have a defensive spine they protrude when attacked, that spine can easily lodge enough tochoke and kill an oscar when and if it trys to swallow the cat.
 
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