What do you think

[BillT]

I know a guy who used to raise tropical fish in a very closed system (no new fish coming in) to sell to wholesalers.
His guppies were never exposed to the outside pathogens and were very susceptible to some nasty guppy virus from Asia and would often get sick when exposed to the outside world. He was pretty pissed off about poeple importing the virus from Asia (in guppies from Asia), since it got around everywhere. Other fish were exposed to it and developed immunity, but his did not.

This involved a specific immunity to a specific pathogen. An organism can't be immune to something it has not been exposed to. Presumably the rest of the immune system worked fine. This would be different from a general immune system malaise. If it immune system were just no working, any old opportunistic bacteria in a tank could invade a fish and eat it from the inside.

I ran a large system with a lot of UV and a pretty good turnover rate. We did bacterial counts in the water in the tanks and it was full of water. Someone there did a study of the bacteria on and in a zebrafish and count (using molecular techniques) something like 16,000 different species of bacteria. This is one of the main reasons i don't think UV alone can eliminate bacterial in tanks.

We also made a completely sterile room and raised sterile fish in there. These fish could survive until about 7 days after fertilization when their egg yolk food ran out. then they died. Their problem was that the right kind of bacteria were required for the inside of the intestines to develop properly. The bacteria would also help digest food. Unfortunately, they died too young to tell anything about the immune system.

[Ron Sower]

I know a guy who used to raise tropical fish in a very closed system (no new fish coming in) to sell to wholesalers.
His guppies were never exposed to the outside pathogens and were very susceptible to some nasty guppy virus from Asia and would often get sick when exposed to the outside world. He was pretty pissed off about poeple importing the virus from Asia (in guppies from Asia), since it got around everywhere. Other fish were exposed to it and developed immunity, but his did not.

This involved a specific immunity to a specific pathogen. An organism can't be immune to something it has not been exposed to. Presumably the rest of the immune system worked fine. This would be different from a general immune system malaise. If it immune system were just no working, any old opportunistic bacteria in a tank could invade a fish and eat it from the inside.

I ran a large system with a lot of UV and a pretty good turnover rate. We did bacterial counts in the water in the tanks and it was full of water. Someone there did a study of the bacteria on and in a zebrafish and count (using molecular techniques) something like 16,000 different species of bacteria. This is one of the main reasons i don't think UV alone can eliminate bacterial in tanks.

We also made a completely sterile room and raised sterile fish in there. These fish could survive until about 7 days after fertilization when their egg yolk food ran out. then they died. Their problem was that the right kind of bacteria were required for the inside of the intestines to develop properly. The bacteria would also help digest food. Unfortunately, they died too young to tell anything about the immune system.

Excellent explanation, Bill!

[LizStreithorst]

agreed.

[Mugwump]

yup, seen a few breeders get anal over sterile tanks too....and they get a rep for weak fish because they have trouble surviving in other folks tanks......