My Oscar

[lreid123]

My 1 foot long Oscar has not eaten in over a week. He stays on side of the tank and rarely lets any of the other fish near him. The tank is 55gal.  He is extremely cranky.  He hits the tank so much until his mouth is red. What is wrong with my Oscar. Linda

[Aleda M Cheng, D.V.M., C.V.A]

I am not a fish expert but I can give you some suggestions.  First there are two valuable web sites than may provide help:

www.oscarfishlover.com/
www.exoticpetvet.net

Oscar’s can go without eating for up to two weeks but banging against the tank sounds like a behavioral problem.  Physical problems must be ruled out first though.

1. Tank Size: Oscar’s need very large tanks so at 55 gallons your tank may not be large enough for a foot long Oscar.  A 75-gallon or larger tank would be more suitable for his size.

2. Oscars have a vitamin C requirement, and giving your Oscar some extra Vitamin C won’t hurt.  You can get the Vitamin C from your pet shop or online.

3.  A parasite or a bacterial/viral infection can alter behavior and appetite.  However these are very difficult to diagnose.  Your Oscar is not showing signs or external parasites but internal parasites are a possibility, and some
parasite infestations show behavior signs.

4.  Water quality must be consistently good and should not fluctuate.

5. Have there been any changes in the environment outside the tank?  Such as moving the tank, changes in lighting, music, or anything else that could upset your fish?

6.  Could your fish be going into breeding season?  This could cause a change in behavior and will resolve once the breeding season is over.

7.  Lastly, Oscars can suffer from indigestion, and an indigestion problem will resolve on  it’s own.

I have included a chart that may help with your treatment protocol.

FRESHWATER FISH PARASITE TREATMENTS

External Parasite and Treatment
1. IchIchthyophthirius multifiliis & Trichodina & Ichthyobodo &Tetrahymena
Salt, formalin, malachite green, other commercial products, inc. temp.

2. Gill flukes, skin flukes
Copper, malachite green, formalin,

3. External protozoa, flukes Velvet (dinoflagellates)
Malachite green and formalin, Antiparasite medication, salt, copper, increase the temp

4. Fish lice, gill maggots
formalin, potassium permanganate, metriphonate, other commercial prod.

5. Anchorworms
organophosphate, manual removal and then dab with antiseptic

6. Larval stage of digenetic fluke parasitesorganophosphate, other commercial products

7. Internal Parasites
Hexamita & Spironucleus, Metronidazole, other commercial products

8. Blood parasites
If flukes: praziquantel, others difficult to treat

9. Nematodes (roundworms)
Use of appropriate anthelmintic drug, eliminate IM host, remove dead fish, piperazine

10. Spiny-headed worm
Praziquantel

11. Digenetic flukes
Difficult to treat, praziquan

Article courtesy of www.exoticpetvet.net

[Jaybay]

I have a 7" goldfish with the same problem and red, irritated tissue around the mouth.  I've tried ick medicine with minimal results.  Kept the tank scrupulously clean, and test the water regularly.  One thing that helped for a while was an antibiotic I got at the pet store.  Oddly, the other fish of the same size has no issues at all.  I'll be interested to read Dr. Cheng's answer.  Hopefully we'll both get some new fish treatment ideas.  :-)

[lreid123]

Thank you for your response.