Im not sure but I think your fish has ammonia poisoning or external bacterial infection which would cause those red streaks on the body.
Ammonia Poisoning
Symptoms: Red or bleeding gills. Fish may appear darker in color and may gasp for air at the surface.
Treatment:Ammonia Poisoning can be prevented but is impossible to cure. Avoid adding expensive fish to new tanks. New tanks must sit for two to four weeks until the bacterial level is sufficient to handle the tank load; add a few inexpensive fish at this time. Purchase an ammonia and nitrite test kit. Test the water until the ammonia drops to nearly zero. At this time, you should notice an increase in the nitrite level. When the nitrites are gone, it will be safe to add fish. Note that the bacterial phases will not take place unless the tank is initially stocked with feeder fish which can be removed after treatment. For larger biological loads, purchase a wet/dry filter (marine only) or a freshwater biological filter such as the Penguin Bio-Wheel by Marineland. For the immediate removal of ammonia, purchase an ammonia detoxifier such as Kordon's Amquel. However, it is best left alone until the bacterial load is sufficient.
Information: Ammonia Poisoning is common in new aquariums, especially when immediately stocked to full capacity. Ideally, the level of ammonia should be zero. Although trace amounts are generally harmless, they can still lead to problems over time. Understanding the nitrogen cycle is essential for the keeping of any aquatic life. In essence, try to maintain your aquarium with no traceable ammonia present. The amount of ammonia present is usually accompanied by a rise in pH. As ammonia is a strong base, it is stabilized by alkaline water. It can cause damage to the gills at a level as small as 0.25 mg/l.
External Bacterial Infection
Symptoms: There are a great deal of possible symptoms associated with this disorder. There may be spots on the body which appear red or orange. Watch for red streaks on the surface on the body. Dropsy (bloating) is also a sign of a bacterial disorder. "False Fungal Infections" look like fungus but is actually a bacterial infection known as Columnaris. These symptoms may include a white or gray film on the body.
Treatment: There are a number of effective treatments for many stains of bacterial infections. Three of the most common are tetracycline, penicillin and naladixic acid. Salt baths are another effective treatment.
Information: Bacterial infections are often difficult to diagnose due to the many different types. Orange or red streaks on the body is usually the only fool-proof method for the determination of a bacterial infection.
