FAQs on Oscar Environmental
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Oscars 1, Oscars 2, Oscar
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Identification, Cichlid Behavior, Cichlid Compatibility,
By far, environmental issues are the principal
cause of Oscar Health troubles:
General malaise, hole in the head and body,
wasted appearance, worn fins... From too high metabolites like
Oscars need space... 55 gallons for one, at
least 75 for two. And redundant, doubled filtration and weekly
water changes w/ gravel vacuuming.
Sent from my iPhone hello my name is Jeannie my husband has Oscars and he
changes the water frequently It looks like the Oscar has a protruding anus
as of what I was told my husband feeds them Oscar pellets and they were
<Correct. This is a prolapse, and Oscars are more prone to these than most
other fish. Partly it's their size and the difficulty people have ensuring
the right water quality, and partly it's their need for a much more varied
diet than some people imagine. Let's pick both of these apart. In terms of
care, Oscars need a large (100+ gallon) aquarium with robust filtration
(water turnover rates of at least 8 times per hour). Water changes should be
weekly. You're aiming for 0 ammonia, 0 nitrite, and, crucially, nitrate
levels below 40 mg/l and ideally below 20 mg/l. All cichlids are sensitive
to nitrate, but unfortunately big, messy fish will raise nitrate levels very
quickly. Having a big aquarium helps dilute nitrate, which is why the 55-75
gallon tanks often recommended in the past for large cichlids don't really
work in the long term -- at least not without much more frequent water
changes. As for diet, Oscars are omnivores in the wild, consuming small
fish, insects and crustaceans as well as fruits and the usual organic
detritus most fish will nibble on when bored. So while something like Hikari
Cichlid Gold makes an excellent staple, it should be augmented with, in
particular, sources of roughage to keep the digestive tract in good health.
Cooked peas are a good choice, with most cichlids eating them when hungry
(feel free to starve them for a week or two if needed) but suitably
gut-loaded insects and crustaceans work well too. Frozen brine shrimp with
added Spirulina are good, as are small crickets. Earthworms are a superb
choice if you have access to a clean supply of them. The foods to avoid are
anything with fat (chicken and beef, for example, though beef heart, using
sparingly, is fine) as well foods known to be unsafe (feeder fish and
I seen this happen after he changed there food please tell me what I can do
to help the Oscar get better.
<Three things to do. The first is to add Epsom Salt to the water. This is
NOT the salt we use in the kitchen, but easily bought online or in
drugstores. Use 1-3 teaspoons per 5 gallons/20 litres. What this does is
work as a mild laxative. Secondly, stop feeding for a week. This will do no
harm to any of the fish in the tank. This gives the digestive tract some
time to recover. And finally, after a week, introduce sources of roughage
into the diet, and only use those foods -- no dried foods or pellets! --
until the fish recovers. Do, of course, check water quality. If you don't
see any signs of improvement, medicating with Metronidazole and an
antibiotic may help, as this combination is widely used with cichlids where
we're dealing with unknown parasites and pathogens.>
He was feed them cichlids gold for about 2 years and about 1 month or 2 ago
he changed it to jumbo minis and that happened
<Hope this helps. Cheers, Neale.>
Oscar health concerns
I have a 125 gallon aquarium with two 10"+ Oscars, one 12" fire eel, and
a jack Dempsey. For their filtration, I use an aqua clear 110 and two 60
gallon sponge filters. Maintenance includes weekly 50% water changes,
vacuuming, etc. Lastly, my water parameters show no sign of any nitrate
or ammonia and is set at 78 F.
<I'm always skeptical of zero nitrate readings. Are you really sure your
nitrate test kit is working properly? Or being used correctly? Zero
nitrate is virtually impossible in an aquarium. You'd need to have zero
nitrate in the tap water -- which is unlikely if you're using standard
tap water in most cities, towns or anywhere near farmland. Pristine well
water might have zero nitrate though. Anyway, most tap water has nitrate
levels somewhere between 10-40 mg/l, and since the filter doesn't remove
it'll only ever go up thanks to the biological filtration process that
turns ammonia into nitrite and then into nitrate. Water changes dilute
nitrate, of course, but that'll half (or whatever) the nitrate level in
tank, not zero it. Furiously rapid plant growth can remove nitrate at
appreciable levels, but you'd need intense lighting and would literally
be cropping the plants back weekly if this was the case. Given your
selection of fish, the idea you have rapid plant growth seems unlikely.
So we come back to the original point, the nitrate surely can't be zero.
Why harp on about nitrate? Because it's the silent killer for cichlids!
Anything above 20 mg/l seems to stress them, and above 40 mg/l there
will be increased
mortality, particularly with the more sensitive species (such as dwarf
cichlids, Tanganyikans, and so forth). Oscars are among the more nitrate
tolerant species, but prolonged exposure does lead to issues such as
Hexamita infection and Hole in the Head disease.>
Overall, I think we have a happy and healthy tank, fish included.
However, I'm concerned with the looks of my butterfly Oscar. Now, he's
always been an ugly boy with his lumps and bumps, but the amount of
slime that covers his body has been progressively increasing.
<Slime generally represents the first line of defence against skin
infections. Assuming no fish have been added recently that might have
introduced, say, Costia, I'd be thinking about Hexamita infections,
I'm worried that it may be in response to something more serious. I've
attached the following video.
<He looks chirpy enough, which is good.>
In general, he seems healthy - eats well (if not the most), swims around
his companions, and has minimal instances of aggressive behavior
(although, he is the moodiest). It's just the looks of him, like a kid
<Indeed. While I'm not seeing the classic pitting you associate with
HITH and HLLE -- yet -- that would be my worry here. The classic
combination of Metronidazole alongside a suitable antibiotic would be my
recommendation if you have access to these. Certainly review nitrate
levels, and if you can,
oxygen levels (high nitrate and low oxygen cause particular stress to
cichlids). While your tank is reasonably large, you've got some big-ass
fish in there, and since they're all carnivores, the sheer volume of
ammonia being excreted will put a lot of pressure on any filtration
Do you know what this might be? Our appreciation goes out to you and WWM
in advance. Thank you!
Sean and Lumpy (the butterfly Oscar)
<Hope this helps. Cheers, Neale.>
Re: Oscar health concerns
A little update for you, because hell, this is what it's all about
<Something like that, yes!>
Now, I was mistaken when I said my nitrate levels were zero -- I didn't
even have a test for nitrate, it was nitrite! Which, were indeed *near*
<Good-ish. You do indeed want zero nitrite, and anything above that can
honestly be a stress factor for many fish, even below 0.5 mg/l. Cichlids
are notoriously sensitive to ammonia and nitrite compared with, say,
Danios or Corydoras, which is why the latter have been used to mature
new tanks, whereas cichlids almost never are. If you're detecting any
nitrite at all, you probably need to decrease stocking, decreasing
feeding, or increasing filtration, because the filter isn't keeping up
with the amount of ammonia excreted by your fish. The backlog, so to
speak, is the nitrite you detect.
The only exception here might be if the tank is relatively new, with a
filter less than 6 weeks old, in which case the nitrite part of the
biological filtration maturing process might not be completed yet.>
Having to get a test for nitrate, I bought some 5 in 1 API test strips
and found the following: GH 0 mg/L, KH 0 mg/L, pH 6.0, nitrite 0-0.5
mg/L, and nitrate 80+ mg/L.
Immediately, I knew it was time for a water change and I even fasted
them for a few days in hopes of mitigating the amount of ammonia they
might produce until the situation was under control.
<Part of the solution, yes; but more frequent or more substantial water
changes are the usual way of minimising nitrate.>
Taking your advice, I did a full Metronidazole treatment and the results
couldn't of been better!
Whether this was the solution to my problem or not -- I know it is not
the magic formula in having long term success. Unfortunately, I don't
have the equipment to test the oxygen in the tank, but with tons of
surface agitation and very few "dead spots," I don't see this as being a
Having been about a week, everything looks great and I couldn't thank
<Glad to help.>
However, my waters nitrate levels still seem to be considerably high
based on your suggestions -- that is, somewhere between 20 and 40 mg/L
in the tank and nearly 20 mg/L out the tap.
<So this is, realistically, the minimum nitrate level you'll have in
your aquarium. Not the end of the world, but you have to accept that
this is not ideal for cichlids. Frequent water changes, light stocking,
and minimal food input are the main things you can do here. In other
words, ensuring the nitrate creeps up as slowly as possible. Oscars are
greedy, but they're also omnivores, so with luck you can offer bulky,
but less protein-rich, foods that will result in less ammonia. Many will
eat peas and other vegetables, which is a good start. Otherwise, just be
really, really careful not to overfeed.>
Is there anything I can really do here? Or is it time to enjoy the fish?
<A little from column A, a little from column B. Yes, you should be
trying to manage the nitrate, but yes, if the fish has perked up, and
you can keep nitrate below 40 mg/l, you should be fine. If practical,
'cutting' tap water with deionised water or rainwater will obviously
reduce the nitrate a lot. Nice Fire Eel, by the way! Cheers, Neale.>
A little help please: Sick Oscar
I think my Oscar is sick.
I haven't seen him eat in weeks.
<Not a good sign.>
Originally ( a few weeks ago ) he was laying on the bottom with shallow
breathing and raggedy fins... Over the past few weeks I have done more
frequent water changes and have also treated for ich, protozoan
parasites, and bacteria infection. (One treatment at a time).
<What did you suspect was the issue? And what medications were used?>
I used Melafix as well.
<Unreliable at best, and harmful at worst.>
His outward appearance has improved.
However he is still not himself. He doesn't eat and floats vertically
upright or face down most of the time which is unusual for him. He can
swim if he wants to but he seems to like to just relax vertically these
I'm not sure if he's really sick or if I'm just not used to this new
behavior... Please help!
<There's a bunch of things here. The first is the inevitable "have you
given him feeder fish to eat" question. If the answer is "yes", then all
bets are off. Feeder fish individually pose a serious risk by
introducing parasites and pathogens, and used frequently cause serious
problems through excess fat and thiaminase, both found in cyprinids
(such as goldfish and minnows). The second question is whether your
Oscar receives fibre-rich foods, such as peas, in its diet. Oscars are
prone to constipation, and while they're not wild about veggies, they
will eat them if sufficiently motivated (i.e., starved) and would do so
naturally in the wild. Anyway, my default assumption here would be
something along the lines of Hexamita if you weren't using feeder fish,
and could rule out constipation because you were offering a balanced
diet including a source of fibre. Hexamita is treated with
Metronidazole, ideally alongside an antibiotic. Remember to remove
carbon from the filter, if used. If you have been using feeder fish,
it's simply impossible to guess for sure what the problem is. Hexamita
plus a Nitrofuran antibiotic would be a good starting point, but you
might find you need to follow up with a dewormer in due course. But who
knows? Feeders are called 'parasite bombs' with good reason, and it's
hard to know what horrible pathogens they're bringing into an aquarium.
Hope this helps,
Re: A little help please: Sick Oscar
Thank you Neale. Before he stopped eating he was eating and probably
overfed Hikari pellets.
<An excellent and well-balanced food, but yes, avoid overfeeding because
they contain little/no fibre. Do offer some green foods, or at least
safe frozen or live foods gut-loaded with plant material; earthworms for
Every time some one passed the tank he begged for food and I let all
visitors feed him but didn't feed him any feeder fish prior to him being
sick. I put some guppies in a few days ago.
<While Guppies don't contain fat and thiaminase, they are a potential
parasite source -- unless you've bred them yourself of course, and know
them to be 'clean'.>
He followed them around for a min but then lost interest. I didn't see
him eat any. I assume they were sucked up in the filter...
Where can I purchase the Metronidazole and Nitrofuran?
<Seachem Metroplex is the standard Metronidazole medication of the
hobby; a vet can also prescribe/sell this in countries where Metroplex
When it comes to Nitrofuran drugs, API produce a product called
Nitrofurazone, Hikari something called BiFuran+, and Seachem have a
product called Focus. I'm sure there are others, and again, outside the
US, similar medications will be available from vets. In Europe and the
UK, you may be able to get hold of something called eSHa HEXAMITA which
isn't Metronidazole, but is available over the counter (rather than from
a vet) and has been used with some degree of success against a range of
Hexamita-type cichlid problems. Definitely worth a shot if you can't get
Metronidazole easily. Cheers, Neale.>
Re: A little help please: Sick Oscar
Many Thanks Neale!