Water changes for 90 gallon Oscar

pops

Alligator Gar
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My apolagise. I was being very terse in my response. I tend to be chaste in my responses to water changes these day, by all means do the water tests and find out what your water change schedule needs to be, I "personally" do fin level wither they need it or not. (I run on the better to much than not enough philosophy), 180g, 100g, 75g, 75g, 40g.
 

David R

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You're a keen man doing fin level changes on those tanks, and I'm sure your fish appreciate it. I'd love to be able to do it, or at least run a drip or semi automated set up, but having a very finite supply for the house makes it impractical for me. Also having tap water that is completely devoid of mineral hardness means if I do big changes the incoming water needs to be remineralised to a certain degree to avoid crashing the pH.

I don't think anyone will disagree that big changes are great if you can manage it and your tap water is suitable.

Sent from my Nexus 5 using MonsterAquariaNetwork App
 

Darth Nandopsis

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You probably don't see a great deal of huge Oscars due to the fact that many fish-keepers simply don't do enough WC's....the more WC's you do, the bigger your fish will grow...combined w/ sufficient room to grow & healthy diet, Oscar can & will get to be 16"+....& the reason you don't see many that big in the wild is that they would in fact be a part of the food chain in the wild.....there are other predators in the wild that would find Oscars a great source of sustenance, such as herons, alligators, etc. Fish are not the only predators that frequent the waterways in FL...:evil_lol:

But to answer the question based on my 43+ years of fish-keeping, mostly keeping SA/CA cichlids? A single specimen Oscar kept in a 4FT tank would require bare minimum 90% WC per week to thrive......& isn't that the goal of "this thing of ours"? Aquariums are glass boxes....lots of stuff going in, & regardless of filtration, unless you do massive WC's @ least weekly, not a lot going out. You simply cannot do enough WC's on a cichlid tank, bottom line.
 

RD.

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Assuming the food is 10% moisture and 50% protein, that adds 1.2 grams of ammonia daily. In 80 gallons of water, that is adding ~4ppm of nitrates daily.

Thanks for crunching the numbers Dr, but the one flaw I see is that an adult oscar (along with most tropical species) does not require a diet containing 50% crude protein. A maintenance diet for most of the larger cichlids kept in captivity would be more in line with 35%, 40% being a max value. As long as the lipid values are in balance the fishes energy needs will be met, and the rest can go to normal metabolic functions, including growth. Even some of the largest carnivorous species kept in captivity (sturgeon) once past fry stage are raised out on pellets that contain 40-45% protein. 50% protein for an adult oscar is excessive, and in this scenario throws off the rest of your calculations.


On a side note with regards to adult size, I would think that with most species that we keep in captivity ones goal should be to mimic as close as possible what we would typically see in the wild. Even though I can raise a mbuna such as an L. caeruleus to 7-8" in captivity, shouldn't ones goal be to match the 3-4" that one would experience in their native habitat? Keeping fish shouldn't be a contest to see who has the biggest. I've seen lots of oversized fish over the years, most were obese and destined for a shorter life than had they been fed more in moderation.

And Darth, using your logic we shouldn't see 12-13" Midas in the waterways of Florida either, yet fish that size are quite common.
 

Darth Nandopsis

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And Darth, using your logic we shouldn't see 12-13" Midas in the waterways of Florida either, yet fish that size are quite common.[/QUOTE]

I was simply responding to another member's suggestion as to why you wouldn't see fish in that size range in the wild. Just a supposition, as we know predation does take place & fish are not on the top of the food chain. I have seen videos of Midas being caught in FL on YT on rod & reel, but nowhere near that size range.
 

Darth Nandopsis

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It took me longer to watch this, than it did to find it. 12", 2.2 lbs according to the scale on hand.

http://www.youtube.com/watch?v=olyBI-ZDFPA

This one is 13", 2.9 lbs.

http://www.youtube.com/watch?v=lbTXGO9QwqA

If adult midas that bright in color can escape predation in a FL canal, so can a full grown oscar.
I'm sure that they can...again, it was just a hypothesis, responding to another members question....& I do know that there are wild reproducing populations of invasive species in FL & other states of cichlids & other species......but we also all know that people do dump large fish that they no longer want into our waters, again in FL & elsewhere....you can find snakeheads & flathead catfish in PA, far bigger than 12"......I never stated that there weren't, just that predation may be the cause of why you don't see any huge Oscars in the wild, which was the other members statement, not mine. I'm also pretty sure that if someone caught a 16" Oscar in the wilds of FL, there would be a video of it. Not stating that they aren't in the waters, but they aren't common-place, either.

"I did some searching, and the average size Oscar caught in the Florida canals is 10". Is the average aquarium specimen really likely to grow considerably larger?"

FYI, this is the post I was responding to. I think we should stop hijacking this thread for an argument that could go on endlessly.
 

RD.

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No offense meant Darth, but I'm with David, 16" oscars might as well be 16" unicorns, I have yet to see one that size in captivity. You stated that Oscars can & will get to be 16"+, yet with all of the millions of oscars out there in aquariums, no one has any actual proof of an O that size. Hmmmmm. But just for arguments sake, lets say that an O could reach 16" or better, that certainly wouldn't be the norm, anymore than a 15 or 16" midas. On average, oscars reach 12" in captivity, give or take an inch or two. So typical max size would fall into the 13-14" range. Not 16"+. Splitting hairs maybe, but all of this becomes relative when one is referring to water changes, the food consumed, and the amount of waste produced by these fish when kept in an aquarium.
 

David R

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Darth Nandopsis said:
You probably don't see a great deal of huge Oscars due to the fact that many fish-keepers simply don't do enough WC's....the more WC's you do, the bigger your fish will grow...combined w/ sufficient room to grow & healthy diet, Oscar can & will get to be 16"+...
I got plenty of good food while growing up, loads of open space and fresh air on the farm yet I'm only 6'1", how come I'm not 7'+ and cleaning up in the NBA (aside from my terrible co-ordination)?

Answer; genetics. IMO oscars, generally speaking, can't and won't get to 16" regardless of how well cared for, in the same sense that the average man isn't going to hit >7' regardless of his lifestyle. As RD. said, for any species there will be a "typical" max size that is +/- an inch or so and that is where the vast majority of specimens will top out. There is bound to be the occasional exception that either gets a bit bigger or a bit smaller, and and even smaller number of "freaks" that gets considerably bigger or smaller. There may well have been the occasional 16" oscar somewhere along the way (though without some sort of recorded proof I'll remain sceptical), but to me saying that the species will grow to 16" (or even 18" as I've occasionally seen claimed) is akin to saying that people will grow to over 8' tall based on a handful of world records.
 

robham7770

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Just my 2 cents, but I think using wild caught florida oscars as an example is fundamentally flawed. Oscars are SA, and in their natural environment do not have to contend with the temp fluctuation present in a south Florida canal. I would think that the Midas from CA is definitely better adapted to the conditions in Florida and would grow faster,bigger, and generally have a good life there. My guess is that for several months out of the year an Oscar would have a hard time in Florida, and would more easily develop heath issues, and also be more vulnerable to predation. It would be interesting to see a comparison of true wild caught oscar size to the invasive florida oscars. Since there is an abundance of really wicked predators in the Amazon, it might not really be very different.
 
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