Introduction: Aquaria Fish Models of Human Disease Ronald B. Walter* Department of Chemistry and Biochemistry, Southwest Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX 78666-4616, U.S.A. The  complete  sequencing  of  a  human  genome  propelled science  into  what  is  often  termed  the  “postgenome  era.” From  a  biological  perspective,  it  is  poignant  to  recognize that  the  completion  of  the  human  sequence  also  signaled the entry into an era of comparative genomics. Comparative genomic  studies  using  model  organisms  facilitate  our  un- derstanding  of  the  common  genetic  elements  associated with  phenomena  such  as  stress  response,  disease  and  its progression, basic physiological mechanisms, and behavior, all of which may involve both environmental and hereditary components.  The  scientific  power  offered  by  comparative genomics  makes  it  likely  that  several  complete  genomes from various vertebrates will be characterized over the next decade. The judicious choice of organisms for detailed ge- nomic  analyses—those  representing  evolutionarily  distant relationships and diverse lifestyles—will greatly advance our understanding of life on this planet. No group of investigators is better poised to promote and  benefit  from  comparative  genomics  than  those  who work  with  teleost  model  systems.  Comparing  the  gene  se- quences of fish and humans has proved to be informative in determining  the  variable  and  constrained  (or  conserved) regions  of  proteins.  The  evolutionary  divergence  and  ex- treme diversity among bony fishes (>18,000 species, an or- der of magnitude more than mammals) provide a wealth of vertebrate  genomes,  each  possessing  unique  and  valuable information on protein structure and function. From a bio- medical  viewpoint,  having  comparative  genetic  data  from several fishes and mammalian species precludes the need to sequence hundreds of individual human genes to determine regions of allelic drift or domains of protein activity. Prob- ably all possible structure-function combinations have oc- curred  in  nature  over  the  past  400  million  years;  much valuable comparative data might well be gleaned from ex- tant fish species. For these reasons, experimental fish mod- els are attracting increased scientific interest. Ensuring that fish  models  maintain  a  robust  presence  in  our  national scientific infrastructure, as part of a larger focus on research with nonmammalian models, is of considerable importance to our long-term scientific strength. Many aquaria fish models currently used in biomedical research possess several attractive attributes: (1) ease of gen- erating large numbers of animals; (2) availability of inbred stocks  and  standard  strains;  (3)  ability  to  make  genetic crosses  among  phenotypically  diverse  fish;  (4)  reasonably well-marked  gene  maps  for  some  species;  and  (5)  genetic mechanisms that correspond to rodent and human models. This  range  of  advantages  has  helped  to  make  aquaria  fish models  attractive  as  research  resources  to  investigators worldwide. Further  development  of  these  models  will  depend  on the amelioration of current infrastructural constraints. We must (1) increase the availability of standard genetic stocks to the scientific community at large; (2) improve develop- ment and access of transgenic fish lines and select mutant fish;  (3)  continue  to  saturate  fish  gene  maps;  (4)  further characterize  molecular  markers  and  cloned  genes  as  re- search  tools  in  a  variety  of  scientific  disciplines;  and  (5) Received January 31, 2001; accepted March 30, 2001 *Corresponding author: telephone 512-245-0357; e-mail RWalter@swt.edu Mar. Biotechnol. 3, S1–S2, 2001 DOI: 10.1007/s10126-001-0020-7 © 2001 Springer-Verlag New York Inc. Next