The Gospel of Thomas exists as the second tractate of the second Nag Hammdi Codex (II,2) as well as in several Greek fragments found at Oxyrynchus.
For this blog post and the following ones, I will rely upon the critical edition by Bentley Layton (Brill).
The first saying within the Gospel of Thomas that includes mention of animals is Saying 3. It exists in both Coptic and Greek (or at least partially in Greek). It is a fairly long saying, so I will dedicate a whole posting to it.
Coptic Text (Layton edition):
ⲡⲉϫⲉ ⲓ̅ⲥ̅ ϫⲉ ⲉⲩϣⲁϫⲟⲟⲥ ⲛⲏⲧⲛ̅ ⲛ̅ϭⲓ ⲛⲉⲧⲥⲱⲕ ϩⲏⲧ ⲧⲏⲩⲧⲛ̅ ϫⲉ ⲉⲓⲥϩⲏⲏⲧⲉ ⲉⲧⲙⲛ̅ⲧⲉⲣⲟ ϩⲛ̅ ⲧⲡⲉ ⲉⲉⲓⲉ ⲛ̅ϩⲁⲗⲏⲧ ⲛⲁⲣ̅ ϣⲟⲣⲡ ⲉⲣⲱⲧⲛ̅ ⲛ̅ⲧⲉ ⲧⲡⲉ ⲉⲩϣⲁⲛϫⲟⲟⲥ ⲛⲏⲧⲛ̅ ϫⲉ ⲥϩⲛ̅ ⲑⲁⲗⲁⲥⲥⲁ ⲉⲉⲓⲉ ⲛ̅ⲦⲂⲦ ⲛⲁⲣ̅ ϣⲟⲣⲡ ⲉⲣⲱⲧⲛ̅ ⲁⲗⲗⲁ ⲧⲙⲛ̅ⲧⲉⲣⲟ ⲥⲙ̅ⲡⲉⲧⲛ̅ϩⲟⲩⲛ ⲁⲩⲱ ⲥⲙ̅ⲡⲉⲧⲛ̅ⲃⲁⲗ ϩⲟⲧⲁⲛ ⲉⲧⲉⲧⲛ̅ϣⲁⲛⲥⲟⲩⲱⲛ ⲧⲏⲩⲧⲛ̅ ⲧⲟⲧⲉ ⲥⲉⲛⲁⲥⲟⲩⲱ(ⲛ) ⲧⲏⲛⲉ ⲁⲩⲱ ⲧⲉⲧⲛⲁⲉⲓⲙⲉ ϫⲉ ⲛ̅ⲧⲱⲧⲛ̅ ⲡⲉ ⲛ̅ϣⲏⲣⲉ ⲙ̅ⲡⲉⲓⲱⲧ ⲉⲧⲟⲛϩ ⲉϣⲱⲡⲉ ⲇⲉ ⲧⲉⲧⲛⲁⲥⲟⲩⲱⲛ ⲧⲏⲩⲧⲛ̅ ⲁⲛ ⲉⲉⲓⲉ ⲧⲉⲧⲛ̅ϣⲟⲟⲡ ϩⲛ̅ ⲟⲩⲙⲛ̅ⲧϩⲏⲕⲉ ⲁⲩⲱ ⲛ̅ⲧⲱⲧⲛ̅ ⲡⲉ ⲧⲙ̅ⲛ̅ⲧ̅ϩⲏⲕⲉ
English Translation (Mine):
Jesus said, “If those who lead you say to you, ‘Behold, the kingdom is in the sky,’ then the birds of the sky will go before you. If they should say to you, ‘it is in the see,’ then the fish will go before you. But the kingdom, it is inside of you and it is outside of you. When you come to know yourselves then you will become known and you will understand that you are the sons (children) of the living father. But if you do not come to know yourselves then you become impoverished and you are poverty.
I have just focused on the Coptic for now rather than matching the Greek from Oxyrynchus. My translation is largely close to most out there. I should make a special note: most translate ⲧⲡⲉ as heaven, but I prefer sky due to the parallel to water. Most ancient languages use the same word that we differentiate into sky and heaven. So, ⲧⲡⲉ can be translated either way. It may have a greater theological “punch” to say the Kingdom is not in heaven(!), but I still think the parallel to water makes the translation to “sky” preferable in this particular case.
What most people notice first here is the idea that the Kingdom is not is a particular place, but it is inside and outside of you. It is, in that sense, everywhere. The go-to parallel is Luke 17:20-21, where Jesus says it is not here nor there, but it is inside of you.
There are, indeed, many parallels – canonical, extra-canonical, etc. – that one can find and that have all been collected by scholars.
But the Gospel of Thomas, Saying 3, is the only one I have seen (so far) that uses animals – here, birds and fish – to illustrate where the Kingdom is NOT. I admit, I have not reviewed everything on Thomas to see what scholars have said about the birds and fish here, but I have a feeling most people are distracted by the part that comes next in the saying.
The passage relies upon an anthropocentric logic that assumes that birds and fish should NOT go before / precede / or arrive before a human being. It assumes, for some reason, that would be a bad thing. Therefore, there is not pie in the sky; there is only pie inside of you!