Silver Tipped Shark Catfish

[Cloud7]

My husband and I got interested in these fish a few weeks ago. We chose a bad time for our impulse to buy them, but the set up is correct. I have researched them to the extent of creating a proper tank for them. I have a 10 gallon tank that is freshwater, but we are moving soon, and our new house has a 250 gallon tank already prepared. They are going to be housed for about 2 months in this smaller tank, but I have read that it is okay to home them in a smaller tank for a short period of their adolesence. We brought home 2 today from PetSmart. One was very thin and black as night, the other, a very beautiful glittery silver with grey fins, and very plump. After aclimating them, they were so very active and I was afraid they would over exhaust themselves. Well, we left for work, and made sure all of the levels and temp was correct. We just came home after an 8 hour shift, we came home to find the thinner, black one dead at the bottom of our tank. We were devestated! The silver one is still active, and shows no signs of any disease I could research. We retrieved the deceased shark, and inspected him for any signs of illness. No spots (ick), or any signs of injury (from fighting with the other), so we are stumped. Maybe just a lemon fish from a petstore? I am concerned for the life of the other. Should I buy more of the breed? I have read that they are social and I was advised to buy them in pairs. We only have one tankmate for him at the moment, which is a sucker fish, who has been very chill. The petstore attendant advised against pairing them in the same tank, with the Silver Tipped's aggression, but I consider myself to have higher judgement then her warning. Also, I want to create a brackish enviroment for the sharks, if I am advised to buy more of the fish, but have a few questions:
1. How do I slowly add the aquarium salt? I dont think I can do it all at once, but slowly change the water woth the added salt?
2. Should I keep just the one shark for now, in risk of just dooming more fish?
3. Can the sucker fish handle a brackish enviroment?
4. Are bloodworms the best diet?
5. Our tank is at an average temperature of 75, but we like to turn the AC down at night, which flexuates the tank temp between 73-79 degrees in the coarse of a day. Is this fluxuation safe if it is gradual throughout a day?
6. When I transport the fish to the bigger tank, how long should it take for them to acclimate if I float them in bags?

[MLBfan]

1. How do I slowly add the aquarium salt? I dont think I can do it all at once, but slowly change the water woth the added salt? I'll let someone more knowledgable on that answer that
2. Should I keep just the one shark for now, in risk of just dooming more fish? yes
3. Can the sucker fish handle a brackish enviroment?no
4. Are bloodworms the best diet? the best diet would be a good varied one I found this

http://animal-world.com/encyclo/fresh/catfish/sharkcat.php][/url] Foods and Feeding

Shark Catfish are omnivorous but prefer meaty foods. As juveniles, they will generally eat all kinds of live, fresh, and flake foods. To keep a good balance give them a high quality flake food or pellet everyday. As they grow go to either pellets or live foods.

Diet Type: Omnivore Flake Food: Yes Tablet Pellet: Yes Live foods (fishes, shrimps, worms): Some of Diet Vegetable Food: Some of Diet Meaty Food: Some of Diet Feeding Frequency: Several feedings per day - This fish grows quickly and as such requires a large quantity of high quality food.

5. Our tank is at an average temperature of 75, but we like to turn the AC down at night, which flexuates the tank temp between 73-79 degrees in the coarse of a day. Is this fluxuation safe if it is gradual throughout a day? Do you have a tank heater
6. When I transport the fish to the bigger tank, how long should it take for them to acclimate if I float them in bags? I'll let someone more knowledgeable answer that.

Is the ten gallon cycled?
Is the 250 gallon cycled?
How often do you do water changes?
What is the footprint (LxW) for the 250?
What size tank is the pleco in?
Do you have a heater for the tank?

[Cloud7]

Unfortunately, the other died sometime last night. :( Im just going to give up on fish for a while.. I guess I have a "dry thumb." Thanks for the help!

[geeman85]

never give up! read read and read the more you know about a specific species the better chance you'll have of it surviving and be able to enjoy the beauty of the fish.