i have less than 5 gallon aquarium with 26 crypt plants, 2 guppies and 3 neon gouramis. i wanted to know does my crypt plants need co2 injection or it is not recommended, please some one suggest me.

You sure it's a 5gallon? that is a lot of plants for a 5 gallon.

that said co2 IMHO is not needed.

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

Welcome to the forums!

Crypts,depending on the species needs little more than light.They are considered one of the easiest types of plants as they dont need high light or CO2,and will be happy in most any substrate.

I think if it truly is less than five gallons those fish need much more room to live a happy healthy life.

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I guess they could be baby Crypts, like the little ones that come off of the mother plants. Still a ton of plants for such a small tank. Way too many fish also.