From Panda Arowanas:
Tilted (overturned) Gill Covers
Cause
Fouled water as a result of rotting food particles and excretions. The strong presence of NH3, NO2 and NO3 can reduce the content of oxygen in the water.
Space constraint - When the Dragon Fish is growing, it not only needs nutrition, it also needs a lot of room to move about. Otherwise, the gill covers may be affected. They may tilt over.
Change in temperature - The temperature of the water in the aquarium should always be maintained. The sensitive gills can be affected when it is either too hot or too cold suddenly.
Symptoms
At the initial stage, the movement of the gill covers is not regular and breathing is also faster and abnormal. Next, the gill covers may become concave and the edge may curl upwards, causing the gills to be exposed in the water.
Finally, at the serious stage, the fish pushes its head up constantly to the surface for air while at the same time loses its appetite. This means the internal gills have become damaged and probably infected with bacteria, affecting the function of breathing and this can lead to death eventually.
Cure
When it is first discovered that the Dragon Fish is not breathing properly, the water should be changed immediately. Every 2 to 3 days, 20% of the water in the aquarium should be changed. Air pump should be further activated and air bubble stones could be added so that oxygen level in the aquarium could be increased. Also, change the filter media to coral sand.
Next stage
When the edge of the gill cover is slightly curled but not yet hardened, other than changing water, and increasing air/oxygen supply, strong water current could be created. There may be 50% chance of a cure without the need to operate.
Final stage
When the gill cover is tilted and hardened exposing the gills, the only way left is to trim off the tissues of the tilted region. Tools needed are scissors, surgical spirit, gloves, plastic bag and a rubber sheet. Also water-proof fine sand paper to polish clean the gill cover affected by cut tissues. The above tools must be properly sterilised.
When all equipment have been properly treated, the Dragon Fish should be transferred to a smaller fish-tank leaving the original tank to be filtered and pumped with air to increase oxygen content. With 1/3 of water in the small tank, anesthesia should be administered within the plastic bag which contains the sick Dragon Fish. It must be established prior to the operation that the Dragon Fish has completely lost consciousness before it can be removed (take care not to cause dehydration). Then use a clean pair of scissors to trim the edge of the gill covers.
After cutting, it is necessary to apply antiseptic medications to the trimmed edges. The Dragon Fish should be promptly put back into its own aquarium to await its regaining of consciousness. More antiseptic medication may be added to prevent wound from being infected with bacteria.
When it regains consciousness, switch off all lights and allow the Dragon Fish to recuperate. Feeding can be stopped if it has no appetite. Additional equipment may be fitted to create waves in the aquarium. The cut portion must grow again before the operation is considered successful.
From Dragon Fish Industry:
Subject: curling gill problem
I'm an enthusiast hobbyist. I enjoy very much in keepingthe asian arowana but I have a problem with these fishes. They always havegill curling. How do you prevent this and what is the best way to curethis disease. How do fix this on a grown fish who had it for quite a while.Thank you for your expert advise .
Answer 2
Normally the gills cover of the Arowana curling isdue to bad water quality and lack of swimming space . ie too small a fishtank for the fish . It happens only to fishes of 12 inches and above .What is the size of your tank ? To correct this problem, you can performa minor surgery on the fish - The procedures are as follows: First, anesthesiathe fish by adding chemicals or lots of ice. Place the fish on a wet pieceof cloth. Heat the small pair of clean scissors and cut the curled partof the gill cover. Finally, apply some anti bacteria powder on the partconcerned. Put the fish back to the tank. The recovery time from the gill-cuttingoperation ranges from 3-6 month for a Arowana about 12 inches to 10 to18 months for a Arowana about 20 inches .
Quote from Jurassic Fishes (Haruto Kodera):
Gill Curling
When the covering of the fish's gills curls back to expose them, this may be caused by either a high concentration of nitrates or a lack of swimming space. In any case, this is a danger signal that must be heeded. The specimen is not in immediate danger of dying, but treatment should not be put off. Change the water frequently, create a more relaxed environment for it, and give it high-quality food. In short, take especially good care of it, and it should recover.
