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FAQs on Oscar Environmental Disease/Health 

Related Articles: Freshwater DiseasesIch/White Spot Disease, Freshwater MedicationsOscars, Neotropical Cichlids, African Cichlids, Dwarf South American Cichlids, Cichlid Fishes in General

Related FAQs: Oscar Disease 1, Oscar Disease 2, Oscar Disease 3, Oscar Disease 4, Oscar Disease 5, Oscar Disease 6, Oscar Disease 7, Oscar Disease 8, Oscar Disease 9, Oscar Disease 10, Oscar Disease 11,
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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 Nitrate.

Oscars need space... 55 gallons for one, at least 75 for two. And redundant, doubled filtration and weekly water changes w/ gravel vacuuming.

Oscars       4/21/20
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 fine.
<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 Tubifex).>
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 MOV   2/24/19
<Hello Sean,>
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 nitrate, 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 the
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, HITH, and HLLE.>
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 with acne.
<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 system.>
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      3/3/19

Hi Neale,
A little update for you, because hell, this is what it's all about right?
<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* zero.
<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!
<Good oh!>
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 problem.
Having been about a week, everything looks great and I couldn't thank you enough.
<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      6/5/18
I think my Oscar is sick.
<Oh dear!>
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.
<That's good.>
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 days?
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      6/5/18

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 example.>
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 isn't sold.
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      6/5/18

Many Thanks Neale!
<Most welcome.>

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