I'm not really aware if they have allergies, but your fish may be a little more sensitive to Swim Bladder Disorder (SBD) than others (I have heard that double tails are more prone to SBD due to a deformity, but I cannot confirm).
Originally Posted by BettaMiah
No, are they freeze dried? Those cause SB all the time.
They do NOT ALWAYS
cause SBD in fish. While it is true that most fish generally have problems with freeze dried blood worms, that doesn't make it a fact.
How are you feeding them? Usually bloodworms are fed as a meal REPLACEMENT or a treat, so you don't feed them pellets at all. I tend to fast them on Sunday, then feed them bloodworms on Monday, it works out fairly well for me. I accidentally spilled the bloodworm bottle into Mali's tank one day and I think he gobbled up a fair few before I got him out of the tank to clean it up, and he was fine. No SBD at all.
works well for SBD and other INTERNAL problems because it is a saline laxative, which causes bowel movements and internal liquid removal in the body.
However, he may not just be able to handle bloodworms due to a possible defect so I would probably feed with extreme caution or find other foods (maybe live) to feed him. :D