This document summarizes an experiment on the effects of salinity on freshwater fishes. The experiment involved exposing freshwater fish to three different salinity levels (0%, 5%, and 15%) over seven days and observing changes. At 15% salinity, fish exhibited low energy, rigidity, loss of scales, and secretion from the body. Some fish died within a few days at 15% salinity. Physiological changes and deaths increased with higher salinity levels as freshwater fish lack mechanisms to tolerate saltwater. The results indicate that changes in salinity beyond about 9% can negatively impact or kill freshwater fish due to osmotic stress on their bodies.

1. Salinity effect on freshwater
fishes
Done by: Sumaiah Alghamdi
Hind alsubeie
Submitted to T: Alanood

2. Content
• Introduction
• Material and methods
• Result
• Discussion
• References

3. Introduction
• Salinity is one of the important environmental factors affecting
survival, growth and distribution of many aquatic organisms
optimal salinity levels for growth, survival and reproduction
competence are often species–specific (1)
• In this study we try to find out the ability of freshwater fishes in
adaptation for salinity by measuring different concentration of
salinity which affect the physiological function of the fishes
bodies.

4. Material and methods
Material :
• 3 aquarium in each one 2 fishes .
• The first one is control
• The second one with 5% salt in 1000 ml
water + 150 g NACL salt
• The last one with 15% sal in 1000 ml
water + 50 g NACL salt
Method:
• Watch the experience every day with and
write the changes and deaths in each
aquarium during 7 days.

5. Result
Day
and
date
Aquarium
15% Nacl
Aquarium
5%Nacl
Control Note
D L D L D L
Day 1 2 2 2
Day 2
Day3

6. Result
Physiological changes
• Low energy
• Rigidity in the body
• Loss of scales
• Secretion of substances from the body
• Death

7. Result

8. Discussion
• As the result showed that some Changes in salinity can effect
biota in freshwater directly or indirectly .
• the major limiting factor affecting the survival of freshwater
fishes is seawater and exposure to salinities greater than about
9% is Absence of efficient efficient branchial and renal
mechanisms osmotic stress which increase osmotic pressure and
deterioration of cell function also this effect accompanied by
changes in Na+ K+ ATPase activity ,Co2 level and acid-base
balance(3)

9. Any question

10. Thank you

11. References
• Effect of salinity on survival and growth of giant freshwater
prawn Macrobrachium rosenbergii (de Man)B.K. Chanda, R.K.
Trivedib, S.K. Dubeyb,∗, S.K. Routb, M.M. Bega, U.K.
DasbaDirectorate
• Effect of increasing salinity on freshwater ecosystem in Australia
. D.L .Nielsen ,M.A.Brock , G.N.Rees and D.S.Baldwin
• Effects of salinity on freshwater fishes in coastal plain
drainages in the southeastern U.S Mark .S.Peterson . Michael
.R.Meador